wake-up 1.explain the difference between photosynthesis and cell respiration in terms of carbon...
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Wake-up
1. Explain the difference between photosynthesis and cell respiration in terms of carbon dioxide.
2. What would happen if there were no nitrogen-fixing bacteria?
EOC Review #4: Genetics, Meiosis, and Biotechnology
Meiosis
What is a Gene?A sequence in DNA that codes (has the directions)
for a trait.
What is a Homologous Pair?A pair of chromosomes with similar genes; one chromosome
is from your mom and the other from your dad
Diploid?Formula: 2n
n = the number of chromosomes2 = two chromosomes; homologous pairs
are present-Normal number of chromosomes in organisms body cells
Haploid?Formula: n
n = the number of chromosomes-Single set of unpaired chromosomes (no homologous pairs) found in gametes.
What is a Gamete?
Reproductive cell; Sex cell
Males have sperm and females have eggs
Brief summary of MeiosisProcess in which gametes (sex cells) are made
Need to split apart the homologous pairs; reduce # of chromosomes by 1/2
Homologous Pairs
DNA is Replicated
Process: Meiosis
Homologous Pairs
Meiosis IHomologous
Pairs are separated
Meiosis IISister
Chromatids are
separated
Process: FertilizationCombination of the egg an sperm
Homologous Pairs
Egg Sperm Zygote
Meiosis produces four gametes (sex cells)
with HALF the number of chromosomes
of the original cell
If an organism has 50
chromosomes and it undergoes
meiosis, how many
chromosomes will be present in
the new cells?
Crossing OverExchange of parts between two paired
chromosomes
Meiosis and Crossing Over
Law of Independent AssortmentHomologous chromosomes will separate
independently of each other during meiosis
What is the Benefit of Sexual Reproduction/Meiosis?
Increases Genetic Variation
Mendelian Genetics
Dominant AlleleDOMINANT allele: Expressed trait; Capital
letter, Always first
Recessive Allelerecessive allele: Only expressed if paired with
another recessive; Lowercase letter
What is genotype?Combination of alleles; allele letters that code
for a trait; GENETIC makeup of gene
Types of Genotypes
a. Homozygous Dominant: Two dominant alleles
BB
Types of Genotypes
b. Homozygous Recessive: Two recessive alleles
bb
Types of Genotypes
c. Heterozygous: One dominant and one recessive allele
Bb
What is phenotype?
Physical expression of trait; observable characteristic; physical appearance
Monohybrid Crosses
Christopherson
Punnett Square
Tool used to predict the genotypes and
phenotypes of offspring
What is Monohybrid Cross?
Punnett square using only one trait.
X
If purple is dominant and white is recessive, cross a purebred (homozygous dominant) purple flower with a white flower.
PP pp
PP x pp
P
P
p p
Pp
Pp
Pp
Pp
Example #1A male that is heterozygous for purple hair is crossed with a orange haired woman. Orange is recessive. What chance to they have in producing a purple haired child? Orange haired child?
Example #3A couple is heterozygous for the gene for big nose. They are about to have a child and hope that it has a small nose. Do they have a chance? How much of a chance? B = Big nose and b = small nose
Special Crosses: Incomplete Dominance and Codominance
What is Incomplete Dominance?
• Blending of the dominant and recessive alleles in heterozygous
• 3rd phenotype
Plant: Snapdragons
Red: R White: r or R` or W
Pink: Rr or RR` or RW
What is Codominance?
• Both dominant and recessive alleles are expressed in heterozygous
• 3rd phenotype
Chickens: Feather Color
Black: B White: b
Black and White: Bb
In snapdragons, red flowers are dominant over white flowers. The heterozygous genotype has pink flowers.
Cross a homozygous red-flowered plant with a pink flowered plant. What are the chances of producing
white flowers? (R = red and r = white)
In certain cattle, hair color can be red (homozygous RR), white (homozygous rr), or roan (a mixture of red
and white hairs, heterozygous Rr). When two roan cattle mate, what genotypes and phenotypes of
offspring could be obtained?
Multiple Alleles and Sex-linkage
What are Multiple Alleles?
Three or more alleles for a particular gene
Example: Blood Types
Different Blood Types in Humans
Blood Type A
IAIA
IAi
Different Blood Types in Humans
Blood Type B
IBIB
IBi
Different Blood Types in Humans
Blood Type AB
IAIB
Different Blood Types in Humans
Blood Type O
ii
A man with heterozygous A blood marries a woman that is heterozygous B blood. What blood types will
their kids have?
What are Sex-linked Traits?
Alleles that are attached to the sex chromosomes
Tricky thing about the Y chromosome
The Y chromosome does not hold any alleles
A woman who has hemophilia marries a normal male. They are worried about their children having
hemophilia. Should they worry? Explain.
If a man with normal color vision marries a woman who is a carrier for colorblindness, what is the
probability of their having a color-blind son? A color-blind daughter?
Karyotypes
Christopherson
There are _________ chromosomes in a typical human body cell.
There are _________ homologous pairs within these cells.
What are Sex Chromosomes?Chromosomes that determine the sex of an organism
Typical Female Sex Chromosomes
Typical Male Sex Chromosomes
Autosomes
Autosomes: Any
chromosome that’s not a sex chromosome
•44 Autosomes•22 pairs of Autosomes
What is a Karyotype?Number and appearance of chromosome set
Understanding a KaryotypeHomologous pairs
Sex Chromosomes
Autosomes
Nondisjunction
Failure of the chromosomes to
separate properly during
meiosis
Monosomy
Mono – One
Missing a chromosome
1 instead of 2 chromosomes
Gamete Gamete
Zygote
Turners SyndromeXO-Single X chromosome
Trisomy
Tri – Three
Having an extra chromosome
3 instead of 2 chromosomes
Gamete Gamete
Zygote
Down SyndromeAka: Trisomy
21
There is an extra 21st
chromosome
Human Genetic Disorders and Pedigrees
Christopherson
What is a Pedigree???
Diagram showing a family tree and patterns of inheritance.
Recessive Trait or Disorder
Traits or disorders caused by 2 recessive
alleles
Cystic FibrosisDisease that causes the body to produce unusually thick, sticky mucus that:
•Clogs the lungs and leads to
lung infections • Obstructs the pancreas
• Stops natural enzymes from helping the body break down and absorb food
Types of Pedigrees: Recessive
Present/Affected Genotypes: bb
Absent/Unaffected Genotypes: BB or Bb
HINT: Recessive Disorders skip generations
Generation I-III was skipped
Sex-Linked Trait/Disorder
Traits/disorders linked to sex chromosomes
Color Blindness
Inability to see colors in the normal way
HemophiliaInability of the blood to clot properly
Types of Pedigrees: Sex-linked
Present/Affected Genotypes: XbXb or XbY
Absent/Unaffected Genotypes: XBXB or XBXb and XBY
HINT: Mainly males are affected
Notice the number of males with the trait.
Dominant Trait or Disorder
Traits or disorders caused by a dominant
allele
Affected individuals are homozygous dominant
or heterozygous
Huntington’s Disease
Causes the break down of brain cells, (neurons) in
certain areas of the brain.
Causes uncontrolled movements, loss of
intellectual faculties, and emotional disturbance.
Types of Pedigrees: Dominant
Affected Genotypes: BB or Bb
Unaffected Genotypes: bb
What type of inheritance?
What type of inheritance?
What type of inheritance?
Genomes and Genetic Engineering
Christopherson
Genome(Video - 0:28-2:29)
The complete set of genetic material of an organism
Human Genome Project (24:42-
The sequence of the 3 billion base pairs
(A,T,G,C) in human DNA was discovered.
This means that the sequence of the genes
within our DNA is known
Benefits of the Human Genome Project
1. Improve diagnosis of diseases and
help with early detection of
genetic disorders
2. Gene Therapy-Swapping an abnormal gene for a normal one-Repairing an abnormal gene
What is Genetic Engineering?Technology used to change the DNA of organisms to
create a new useful result
How is Genetic Engineering possible?
1. Isolate GeneSpecific “gene of interest” can be “cut” out of
DNA using restriction enzymes
Restriction EnzymesEnzyme produced by bacteria; cut DNA at
specific base sequences.
2. Place the Gene of Interest into Vector
Vector = Vehicle that “carries gene
of interest”;
Bacteria is the most common.
2. Place the Gene of Interest into Vector
a. Cut the plasmid with same restriction enzymes used on gene of interest
2. Place the Gene of Interest into Vector
b. DNA Ligase attaches the gene of interest to the cut plasmid
c. Form Recombinant DNA.
A gene from one organism is put into
the genome of a different organism.
2. Place the Gene of Interest into Vector
2. Place the Gene of Interest
into Vector
d. Recombinant DNA is placed back
into bacteria cell through process
called TRANSFORMATION
How is genetic engineering possible?Transformation: When a cell
takes up and expresses a new piece of
genetic material—DNA— in order to change the organism’s
traitsDNA Protein TraitRNA
Transgenic OrganismAn organism (animals, plants, and bacteria)
that has been genetically altered.
Example #1: Diabetes and Insulin (Medical)
What is Insulin?Insulin (protein)
helps glucose move from our bloodstream to
our cells
Glucose is from food that was
consumed
Type 1 Diabetes: The Pancreas does not produce insulin
Diabetics need to take Insulin shots
Diabetics need to test their blood sugar
How does someone with Type 1 Diabetes get insulin?
History of Insulin Production (finish)
Gene that makes insulin in humans was inserted into E.coli (Bacteria) which produced synthetic human insulin
Gel ElectrophoresisChristopherson
What is Gel Electrophoresis?Process used to separate fragments of DNA using
a charge
1st Step in Electrophoresis Prepare the gel
Need agarose, mold, and comb
2nd Step in Electrophoresis Prepare the box
Need electrophoresis chamber and buffer
3rd Step in Electrophoresis Load DNA into the wells of the gel using a
micropipette
DNA
Well
4th Step in Electrophoresis
Run electricity to separate DNA
fragments
5th Step in Electrophoresis
Stain the gel to see the DNA fragments
Analyze results
What is the Result?Well DNA Fragment
Shorter Fragments
Larger Fragments
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EXAMPLE I: WHO IS THE CRIMINAL?