UNIT 8: GENETICS

1. What is the molecule responsible for passing on hereditary traits?2. What is it’s structure?

•Deoxyribonucleic Acid (DNA) is a nucleic acid that contains genetic instructions used in the development and functioning of all known living organisms and some viruses•The main role is the long-term storage of information.•DNA is often compared to a set of blueprints

DNA consists of ________ complementary chains of nucleotides

The DNA ladder consists of: U______________: alternating phosphates and deoxyribose R_________: Pairs of nitrogen bases held together by weak Hydrogen bonds

ADENINE always pairs with THYMINE CYTOSINE always pairs with GUANINE

Twisted in to a

double helix

Functional unit: _____________________

ab

c

Nucleotide

PhosphateDeoxyribose

Nitrogen Base Pairs (A, T, C, G)(Sticks and curves)

2

RailingSteps

----

T

A

C

G

Thinking back to reproduction

• If cells are going to replicate and reproduce, each cell needs to get a new copy of instructions (DNA)

• How is that copy made?• (Take out note packets)

3. How does DNA replicate (make more copies of itself)

1. The ladder __________________

It breaks apart at the weak Hydrogen Bonds between the bases.

2. Newly synthesized nucleotides line up by

_________ ________________

Result: ___________________________________ Identical to the first strand and to each other.

Splits

Base Pairing

Two new strands of DNA

Warm Up Question 3/25/10

A

T

C

C

C

Complete the DNA base pair replication for each strand

T

A

G

G

G

T

A

G

G

G

A

T

C

C

C

•exist at different loci (permanent locations) in a linear fashion on chromosomes.•Two genes associated with a specific characteristic are known as _____________ and are located on homologous chromosomes

Pair of allelesIndividual genes

DOMINANT ALLELE: Always exerts full effect, will mask the other gene characteristics

RECESSIVE ALLELE: The gene is present, but not always expressed

Different combinations of alleles result in different patterns of inheritance:

GENOTYPE: Describes the genetic combination

HOMOZYGOUS: two of the same alleles HETEROZYGOUS: two different alleles

PHENOTYPE: Describes the physical appearance

5. What is gene chromosome theory?

Genotype Phenotype

Homozygous

Heterozygous

4. What is a gene?

6. Can offspring have traits that are different than their parents

Gene: __________________________

Gene pool: __________________________

DNA Coding for 1 protein

All available genes in a population

Genes

alleles

Loci for a single alleleLocation

How many genes are on a single chromosome?

• A Lot!• Chromosome 1– Contains over 3000 genes– Contains over 240 million base

pairs, of which ~90% have been determined

• These things are mapped out on chromosome maps

•exist at different loci (permanent locations) in a linear fashion on chromosomes.•Two genes associated with a specific characteristic are known as _____________ and are located on homologous chromosomes

Pair of allelesIndividual genes

DOMINANT ALLELE: Always exerts full effect, will mask the other gene characteristics

RECESSIVE ALLELE: The gene is present, but not always expressed

Different combinations of alleles result in different patterns of inheritance:

GENOTYPE: Describes the genetic combination

HOMOZYGOUS: two of the same alleles HETEROZYGOUS: two different alleles

PHENOTYPE: Describes the physical appearance

5. What is gene chromosome theory?

Genotype Phenotype

Homozygous

Heterozygous

4. What is a gene?

6. Can offspring have traits that are different than their parents

Gene: __________________________

Gene pool: __________________________

Codes for 1 protein

All available genes

Genes

alleles

TT Can Roll Tongue tt Cant roll tongue

Tt Can Roll Tongue

__ __

____ _______ _____

__ __What you can see

T tTongue Roller

T

t

Tongue Roller

T

T

t

t

T T

t t

NOT a tongue Roller!

Journal Time!• Q4: What is a gene?•• • • Q5: What is gene chromosome theory?••• • • • Q6: Can offspring have traits that are different than

their parents? Explain:• • • • • C. What genetic concept does this cartoon illustrate?•• •

Warm-up Match the following terms with their

definitions

1. Homozygous2. Heterozygous3. Allele4. Genotype5. Phenotype6. Dominant7. Recessive

A. One of a paired set of genes that codes for a particular trait

B. Always expressed (Capital Letter)

C. Represented by a Lower Case letter

D. Two of the sameE. Genetic Make

upF. TtG. Physical

Appearance

D

F

A

E

G

B

C

3/26

Law of ____________________: When an individual pure for the dominant trait is crossed with an individual pure for the recessive trait, the physical appearance of the offspring is like that of the dominant parent.

TRAIT DOMINANT FORM RECESSIVE FORM

Stem Length Tall (T) Short (t)

Seed Color Yellow (Y) Green (y)

Pod Shape Inflated (I) Constricted (i)

Seed Shape Round (R) Wrinkled (r)

7. What insights did Mendel give us into patterns of inheritance?

Law of ____________________:When gametes are produced, the genes separate so that each gamete receives only one copy.A gamete will receive one allele or the other.The direct proof of this was later found when the process of meiosis came to be known.

PUNNETT SQUARE SOLUTIONS:

Stem Length: Seed Color: Seed Shape:Pure Tall X Pure Short Hybrid yellow X pure green Monohybrid cross

In the 18th century, an Austrian monk and teacher Gregor Mendel developed some basic principles of heredity without any knowledge of genes or chromosomes.

He experimented with pea plants.

As a result of mathematical analysis of ratios associated with characteristics in the offspring, Mendel proposed that characteristics were inherited as a result of the transmission of hereditary factors.

Dominance

Dominance

• Dominant allele represented by a Capital Letter

• Always masks over any recessive alleles– For example:

Tongue Rolling (T)Not tongue rolling (t)Tt = what phenotype?

(remember phenotype and physical appearance)

Law of ____________________: When an individual pure for the dominant trait is crossed with an individual pure for the recessive trait, the physical appearance of the offspring is like that of the dominant parent.

TRAIT DOMINANT FORM RECESSIVE FORM

Stem Length Tall (T) Short (t)

Seed Color Yellow (Y) Green (y)

Pod Shape Inflated (I) Constricted (i)

Seed Shape Round (R) Wrinkled (r)

7. What insights did Mendel give us into patterns of inheritance?

Law of ____________________:When gametes are produced, the genes separate so that each gamete receives only one copy.A gamete will receive one allele or the other.The direct proof of this was later found when the process of meiosis came to be known.

PUNNETT SQUARE SOLUTIONS:

Stem Length: Seed Color: Seed Shape:Pure Tall X Pure Short Hybrid yellow X pure green Monohybrid cross

In the 18th century, an Austrian monk and teacher Gregor Mendel developed some basic principles of heredity without any knowledge of genes or chromosomes.

He experimented with pea plants.

As a result of mathematical analysis of ratios associated with characteristics in the offspring, Mendel proposed that characteristics were inherited as a result of the transmission of hereditary factors.

Dominance

Segregation

Segregation• Every person has two alleles for any

given trait (one from the mom, one from the dad)

• Offspring will get either one of those• Ex:– Of a mom is Tt for tongue rolling she

can give either the T or the t, and this is determined by chance.

– Same for the father with Tt. He can give T or t

• This is demonstrated by a punnett square

Law of ____________________: When an individual pure for the dominant trait is crossed with an individual pure for the recessive trait, the physical appearance of the offspring is like that of the dominant parent.

TRAIT DOMINANT FORM RECESSIVE FORM

Stem Length Tall (T) Short (t)

Seed Color Yellow (Y) Green (y)

Pod Shape Inflated (I) Constricted (i)

Seed Shape Round (R) Wrinkled (r)

7. What insights did Mendel give us into patterns of inheritance?

Law of ____________________:When gametes are produced, the genes separate so that each gamete receives only one copy.A gamete will receive one allele or the other.The direct proof of this was later found when the process of meiosis came to be known.

PUNNETT SQUARE SOLUTIONS:

Stem Length: Seed Color: Seed Shape:Pure Tall X Pure Short Hybrid yellow X pure green Monohybrid cross

In the 18th century, an Austrian monk and teacher Gregor Mendel developed some basic principles of heredity without any knowledge of genes or chromosomes.

He experimented with pea plants.

As a result of mathematical analysis of ratios associated with characteristics in the offspring, Mendel proposed that characteristics were inherited as a result of the transmission of hereditary factors.

Dominance

Segregation

T Ttt

Tt TtTt Tt

Y yyy

Y yY y

yyyy

R rRr

RRRr

Rrrr

Hybrid = 2 together

Warm up(questions from the box)

1) Why do they call it genetics?

2) What does DNA stand for?

3) Why can someone look more like 1 parent than another?

4) Why are we learning about genetics?

3/29

8. What are some genetic diseases caused by recessive alleles

CYSTIC FIBROSIS•Affects about 1 in 1600 people in the USA•It is caused by a recessive defective gene inherited from both of the parents.•The result is that the body produces thick sticky mucus in the lungs which has to be removed•Excessive mucous occurs in the pancreas causing digestive problems•The most serious problem is the blockage of air passages in the lungs, results in many infections•Both parents must carry the gene, and there is a 1 in 4 chance of their child being born with CF

SICKLE CELL ANEMIA•Causes red blood cells to be shaped like sickles, they get stuck in the capillaries and deprive body cells of oxygen.•Rare in the USA, but common in some African countries. This is because carriers of the disease are more immune to malaria. Hence, being a carrier increased chance of survival.

9. Are there other patterns of inheritance? Are the relationship between genes and traits more complex than Mendel’s Laws illustrate with peas?

MULTIPLE ALLELESMORE THAN TWO ALLELES ARE INVOLVED

BLOOD TYPES in humans. Three possible alleles: ____ ____ ____

EACH INDIVIDUAL INHERITS SOME COMBINATION OF 2 ALLELES Gene Combination Blood

Type

ABABO

Sample Crosses: Mom: Type ABMom: Type O Dad: Type BDad: Type B His mom type o

C cCc

CC CcCc cc

50% carriers

25% withDisease

S sSs

SS SsSs ss

More complex!

Co-Dominance• Remember: Each trait is represented by

the same letter! If there are multiple alleles (expressions) then we need something other than just a capital and a lower case– IB , IA , i

• BOTH alleles are expressed (different than dominant and recessive)

• Both A and B allele are expressed (blood type AB)

• i is recessive (blood type o)• A and B dominate over O, but A and B are co-dominate

IA IB

IB

iAB B A B

8. What are some genetic diseases caused by recessive alleles

CYSTIC FIBROSIS•Affects about 1 in 1600 people in the USA•It is caused by a recessive defective gene inherited from both of the parents.•The result is that the body produces thick sticky mucus in the lungs which has to be removed•Excessive mucous occurs in the pancreas causing digestive problems•The most serious problem is the blockage of air passages in the lungs, results in many infections•Both parents must carry the gene, and there is a 1 in 4 chance of their child being born with CF

SICKLE CELL ANEMIA•Causes red blood cells to be shaped like sickles, they get stuck in the capillaries and deprive body cells of oxygen.•Rare in the USA, but common in some African countries. This is because carriers of the disease are more immune to malaria. Hence, being a carrier increased chance of survival.

9. Are there other patterns of inheritance? Are the relationship between genes and traits more complex than Mendel’s Laws illustrate with peas?

MULTIPLE ALLELESMORE THAN TWO ALLELES ARE INVOLVED

BLOOD TYPES in humans. Three possible alleles: ____ ____ ____

EACH INDIVIDUAL INHERITS SOME COMBINATION OF 2 ALLELES Gene Combination Blood

Type

ABABO

Sample Crosses: Mom: Type ABMom: Type O Dad: Type BDad: Type B His mom type o

each person only inherits 2

C cCc

CC CcCc cc

50% carriers

25% withDisease

S sSs

SS SsSs ss

IA IB i

IA IA IAiIBIB IB i

IA IB

ii

i iIB

iB BO O

IA IB

IB

iAB B A B

More complex!

Sickle Cell AnemiaHeterozygous individuals have a resistance to malaria.(may be why the disease persists in the population)Both alleles expressed

Both alleles expressed

Malaria can not attack the sickle cells(individual unaffected by malaria)

(Warm up)Nature vs. Nurture

• Which has a greater effect on what determines our traits?

CONTINUOUS VARIATION

Results when several genes influence a trait•Height: TTTTTTT --------- tttttttt•Skin ToneMany different variations of the trait are expressed

10. Can patterns of heredity can be more complex?

1. Plants require sun to “turn on the gene” produce green chlorophyll. In the absence of sun, the gene will not be expressed, and the plants will be white.

2. Pigment producing genes of the arctic fox do not function in the winter due to the cold temperature. In the warmer summer, the genes function As a result, the fur is white in the winter and to produce a reddish-brown pigment. the animals blend in to the background. Now the fox resembles the tundra of summer

3. When an icepack is placed on the shaved skin of a Himalayan hare, the fur grows in dark.

4. TWIN Studies (upbringing means the same thing as environment) Twin’s genes are identical, so any difference between them must be caused by

slight differences in their environment throughout their lives.

Ex: Height differences due to differences in nutrition Muscular development in an athlete.

CROSSING OVER during MEIOSIS & GAMETE FORMATION increases variety

11. Can environment influence heredity? Can certain environmental conditions alter phenotypes?

NOTE: only changes in DNA of the sex cells can be passed on to the next generation

*Environment can determine gene expression

Nature vs. Nurture• Which has a greater effect on

what determines our traits?

In other words…• DNA doesn’t necessarily

determine exactly who we are/going to be– More like sets the boundaries in

which we will fall somewhere.– Nature determines where

You

Somewhere in there

Vocabulary Notebooks

• The following terms:–Heterozygous–Homozygous–Allele–Gene–Dominant allele–Genotype–Phenotype–DNA– Sickle Cell Anemia

(checking these?)

Warm up• Give an example of how the

environment can influence phenotype/gene expression.

3/31

Interesting….

• How come there are more color blind males than females?

12. How is the sex of the offspring determined?

13. What diseases are associated with the sex chromosomes?

Diploid cells of organisms contain two types of chromosomes.

Autosomes: ______________________________________

Sex Chromosomes ____________________________________

HEMOPHILIACondition in which the blood does not clot properly.

COLOR BLINDNESSInability to see different colors

Normal Female

Normal Male

CARRIER female

Male with condition

Female with condition

Show the cross: #1 Normal Male 2. Male with hemophilia c> Colorblind male Female carrier for Hemophilia Normal female Carrier female

SEX LINKED TRAITS

• The genes for certain traits are located on the sex chromosomes• Sex linked traits occur more frequently in males.

any chromosome that is not a sex chromosome

Determines the gender of an individualHumans: X and Y(XX = FemaleXY= Male)

Not the same in all organisms!

Gender determination

• Not always cut and dry• Check it out• Sometime not always a simple

genetic basis– Reptiles!– Flies!

12. How is the sex of the offspring determined?

13. What diseases are associated with the sex chromosomes?

Diploid cells of organisms contain two types of chromosomes.

Autosomes: ______________________________________

Sex Chromosomes ____________________________________

HEMOPHILIACondition in which the blood does not clot properly.

COLOR BLINDNESSInability to see different colors

Normal Female

Normal Male

CARRIER female

Male with condition

Female with condition

Show the cross: #1 Normal Male 2. Male with hemophilia c> Colorblind male Female carrier for Hemophilia Normal female Carrier female

SEX LINKED TRAITS

• The genes for certain traits are located on the sex chromosomes• Sex linked traits occur more frequently in males.

any chromosome that is not a sex chromosome

Determines the gender of an individualHumans: X and Y(XX = FemaleXY= Male)

Not the same in all organisms!

X XX YX X’X’ YX’ X’

X XX YX X*X* YX* X*

X YX X’

X X X YX X’ X’ Y

X’ YXX

X X’X X’

X YX Y

X* YXX*

X X*X* X*

X YX* Y

Traits found on the sex chromosomes

(Females have a second X copy)

Warm up

• What the heck were we learning about in class almost two weeks ago?

4/12

I know you’ve been lost without these cartoons…

Warm up

• How many letters are in the genetic alphabet?

• How many different 3 letter combinations could be made with these letters?

• 64 different combinations!

4/13

How can directions code for things?

• For example; CAKE?– How do we go from instructions to

our final product?– (take action)

• How do we go from DNA to traits?– TAKE ACTION

Cool Video #1

• Transcription– Making a copy of instructions to

send out of the nucleus

• Trick to remembering:– Transcribing is just writing it. That’s

all transcription is doing! Re-writing it! (Scribes write things out)

14. How does the information encoded in the DNA produce traits? How does a gene lead to a characteristic?DNA codes for the production of proteins

Traits are proteins, or are produced by the action of a special group of proteins - enzymes.

This is how it works: 1. The DNA code is based on the sequence of nitrogen bases.

DNA stays in the nucleus

2. Messenger RNA copies the code ( ) Single stranded / U instead of T

Set of 3 bases on the mRNA: __ __ __ __ __

3.

5. transfer RNA carries in amino acids anticodons match to codonsAppropriate amino acids are linked

6. Individual amino acids link and peel off to form a

This protein is the trait(such as red pigment) or an enzyme to catalyze a reaction that

produces a trait.

4.

C o d o n

(safe place for info)

mRNA

mRNA leaves the nucleus

DNA mRNA

Modeling

• Now use the pieces to show transcription.– Find the base pair for the new

strand of mRNA that pairs with the DNA. Tape them together one at a time as would happen inside the nucleus to make mRNA

– DNA: White– mRNA: yellow– tRNA: Tan– Amino Acids: Pink

? ? ? ? ? ? ? ? ?

Cool video #2

• Translation– Going from mRNA to a protein– Involves mRNA, tRNA, amino acids

and ribosome

• Trick to remembering:– Translation is translating the code

into a protein.– Like translating a foreign language

into what it means• Hola Hello• GUA Histidine (amino acid)

14. How does the information encoded in the DNA produce traits? How does a gene lead to a characteristic?DNA codes for the production of proteins

Traits are proteins, or are produced by the action of a special group of proteins - enzymes.

This is how it works: 1. The DNA code is based on the sequence of nitrogen bases.

DNA stays in the nucleus

2. Messenger RNA copies the code ( ) Single stranded / U instead of T

Set of 3 bases on the mRNA: __ __ __ __ __

3.

5. transfer RNA carries in amino acids anticodons match to codonsAppropriate amino acids are linked

6. Individual amino acids link and peel off to form a

This protein is the trait(such as red pigment) or an enzyme to catalyze a reaction that

produces a trait.

4.

codonAmino acid

C o d o n

(safe place for info)

mRNA

mRNA leaves the nucleus

To ribosome

Ribosomes bind to mRNA

Protein!!! (translation)

DNA mRNA

Modeling• Translate your mRNA into a

protein by matching up the correct tRNA with its appropriate amino acid1) Match the appropriate tRNA’s with

their amino acids (CAC: Valine, CUC: glutamic Acid, GUA: Histidine)

2) Base pair them with the mRNA, one at a time as it would occur in a cell. (GUG on mRNA would bind to CAC on tRNA)

3) Tape the amino acids together as they come in to form a protein.

4) Work on your journal/Things that you owe me. Tomorrow is the last day to hand in make up work.

RIGHT NOW

• Journal for the page of notes we just covered

• Any other missed work you owe me. For example:– Labs– Classwork / homework– Exams….

Warm up

• Fill in the flow chart using the following terms:– DNA, mRNA, tRNA, Ribosome,

Protein, and tRNA + amino acid

1. 2.

3.

4. 5.

DNA mRNA

tRNA +Amino acids

Ribosome

Protein

transcription

translation

4/14

Whats wrong with the following sentence:

• Thedogbitthemanandran• Should be broken up into words

that mean something!– (The dog bit the man and ran)

• That is what codons are– Broken up into 3 letters, each is one

“word” that codes for a specific amino acid

• GCATTTATGCCCATT– GCA TTT ATG CCC ATT– Each “word” codes for a specific

Amino Acid

Warm up

• What would happen to this sentence if one of the letters was removed or an extra one added but we still read every three letters as a word?

• THE BIG DOG BIT TED AND RAN OFF

• THE BID OGB ITT EDA NDR ANO FF• THE BIG DOG TBI TTE DAN DRA NOF F

• NONSENSE!!!

4/15

What if there was an error like this in our DNA?• Mutations!!!!

15. WHAT CAN GO WRONG?

MUTATION_________________________________________________

Gene mutation: change to the nucleotide sequence of DNAcan be inherited from a parent or acquired during a person’s lifetime

Normal Gene Sequence TAGAAACATAdd an extra base INSERTION TACGAAACATLoss of a base

Substitute one base for another

Section is turned around TACGATACAASection from a nonhomologous chromosome TACGAAATGG

16. What are the consequences if there is an error in replication, transcription or translation?

Both the APC I1307K mutation and mutations that cause FAP occur in the same gene, the APC (Adenomatous Polyposis Coli) gene. Individuals with FAP develop hundreds to thousands of polyps in the colon and rectum and have a very high risk of developing colorectal cancer. The APC I1307K mutation is different from other APC mutations because the mutation itself does not cause colon cancer. Instead, this particular mutation creates an unstable spot in the gene that makes the gene more susceptible to additional genetic changes that may in turn lead to colon cancer.

A LOT!!An error in the sequence of DNA

Gene Mutations

Deletion TAAAACATSubstitution TAGCAACATInversionTranslocation

NONDISJUNCTION: Failure of a pair of chromosomes to separate during meiosis.

DOWN’S SYNDROME results from Nondisjunction of chromosome #21 Results: one gamete provides an extra chromosome to the zygote.

POLYPLOIDY: An extra set of chromosomes is inherited In animals, this condition is almost always lethal

Common in plants. Plants are usually ________________ and _________________

Watermelon (3n) tobacco (4n) Wheat (6n) Strawberries (8n)

19. What are the consequences of a mutation? The code is altered, so there is a change in protein structure and a subsequent change in functionDoes contribute to variety, but most mutations are harmful

17. Can there be a mutation involving chromosome number?

•18. What causes mutations?

Environmental Mutagenic Agents (MUTAGENS Chemicals:

•Formaldehyde•Colchicine•PCB’s

• X-rays• UV radiation

Radioactive Substances:

(like in the karyotyping lab)

Carcinogens: may cause mutations that lead to cancer

(+)’s- Increase variety-Can lead to better things(adaptations)

(-)’s-Messes up instructions-Non-functioning proteins-Cancer-Death-Diseases

Larger More Vigorous

Matching activity.

Warm upsGive an insertion mutation in the

following sentence:The cat ran far

What happens to the message?

4/16

Like Genetics?• There are tons of professions

which deal with genetics• Today we will be looking at

Genetic Counseling (really just scratching the surface) and some things that they do.