unit 3: growth and heredity cells can grow only so big before they need to divide

Unit 3: Growth and Heredity • Cells can grow only so big before they need to divide

Mitosis (Cell Division)• Mitosis• nucleus divides into two nuclei • number of chromosomes remain the same.

Mitosis• Continuous process• 4 Stages of Mitosis

• Prophase (1st Phase)• Chromosomes become visible• Cell part that contains genes that express traits that is located in the

nucleus• Made up of thread-like material-chromatin• Control cell processes and determine traits of the entire organisms

• Nuclear envelope dissolves• Spindle forms (centrioles)• Attach to chromosomes

Mitosis

• Metaphase (2nd Phase)• Chromosomes line up along the equator (middle of the

cell)

Mitosis• Anaphase (3rd Phase)• Centromeres divide ( connects the chromatids together)

• Chromatids are single strands of chromosomes

• Chromatids move toward opposite poles (spindle fibers are getting shorter)

Mitosis• Telophase (4th Phase)• Nuclear envelope forms at each pole• Chromosomes unwind• Cytokinesis begins

Mitosis and Cytokinesis• Cytokinesis-as mitosis ends this process begins• Cytoplasm divides • Forms two new cells• End result of mitosis and cytokensis: 2 diploid (2n) identical cells

Cytokinesis: Plants and Animals• Animals - cell pinches inward • Plants - a new cell wall forms between the two

new cells

The cell cycle is carefully controlled• Checkpoints (traffic lights)-check for errors, correct mistakes

and stop the process.

Mitosis• Purpose:

• Replace old and worn out cells lost by wear and tear. Ex. Skin shedding• Required to sustain life• Immature human=growth

• Mitosis• Type of Cells that divide in this process

• Body cells (hair, skin etc.)

Meiosis• Process by which gametes (reproductive cell) are formed (egg

and sperm cells)• Sperm Cell-male reproductive cell • Egg Cell- female reproductive cell

• Gametes contain half the number of chromosomes as body cells.• Because offspring will get a copy of genes from each parent.• Example: Female Gamete=23 chromosomes and Male Gamete=23-

Zygote (fertilized egg has 46 chromosome)

Meiosis • Form of cellular division that halves the number of

chromosomes• Two cell divisions-meiosis I and II • Total of eight phases • Starts with homologous chromosomes • are similar in shape and content

• End result: 4 haploid (n) genetically different cells.

Chromosomes• Made up of thread like material (DNA) called chromatin

(prophase)• Located in the nucleus (control center of the cell)• Control cell processes and determine the traits of the

entire organisms (hair color, height , eye color etc.)• Comprised of two sister chromatids (single strand of

chromosomes) that are identical in content• During cell division, each chromosome makes an exact

copy of itself.• Genes ( part of chromosome that controls inherited

traits-eye color, height, etc.) are located on different parts of chromosome

Chromosome Structure (Draw)

Meiosis Graphic Organizer (Recopy)

2n

n n

n nnn

MEIOISIS 1

MEIOISIS 2

Purpose of Meiosis • Primary purpose is to increase genetic variations (differences)

Meiosis Provides Variations (Differences)3 mechanisms contribute to genetic variations (Differences)• Independent assortment, crossing-over and random fertilization

Independent Assortment

• Random distribution of homologous chromosomes during meiosis (genetic shuffling)• Siblings look similar but different because they have

some genes in common.

Random fertilization• Only one sperm will fertilize an egg• Each sperm carries a different combination of genes• Allows for unlimited genetic combinations

Only one sperm will enter the egg

Crossing Over• Occurs in Prophase I• Portion of one homologous chromosome is exchanged with a

portion of another homologous chromosome

Importance of Genetic Variation

• Increases the speed of evolution (change)• Allow favorable traits (thick fur) to pass from one generation

to the next that increase chances of survival

Asexual Reproduction (Mitosis)• Asexual reproduction-a single parent passes copies of all of its

genes to each of its offspring• Clone-organism that is genetically identical to its parent

Sexual Reproduction (Meiosis) • Sexual reproduction-two parents each form haploid

reproductive cells (sperm and egg), which join to form offspring. • Have traits from both parents• Not exactly like parents

Advantages of and Disadvantages of each type of reproduction

• Asexual reproduction:• Disadvantage: lack of diversity that threatens the ability of the

organisms to adapt in a changing environment• Advantage: allows organisms to produce many offspring in a

short period of time without using energy

Advantages of and Disadvantages of each type of reproduction

• Sexual Reproduction:• Advantage: enables organism to adapt to changing environment• Disadvantage: requires lots of energy and produce only a few

organisms at a time.

Haploid (n)sperm

Haploid (n)egg

Diploid(2n)zygote

Venn Diagram: Asexual vs. Sexual Reproduction • Insert the following terms into the right part of the circle.• 1. one parent• 2. two parents• 3. clone• 4. different from parent• 5. requires more energy• 6. difficulties adapting to a changing environment• List two similarities in the middle• Explain why genetic differences are important?

Heredity

• Many of your traits (characteristics of an traits (characteristics of an organism)organism)-eye color, hair color-resemble your parents.• Inherited traits: traits that are passed from parents to

their offspring. • Eye Color

• Heredity-passing of traits from parents to offspring• Study of heredity began with Gregor Mendel• Genetics-focuses on heredity

Mendel’s Studies• Based his hypotheses on pea plants• Concluded the following:

1. An individual inherits two copies of a gene-one from each parent

Mendel’s Theories

2. There are alternative versions of genes• Ex. Flower Color: purple and white

Mendel’s Theories

3. Some traits are expressed and others are hidden.• Dominant: gene whose trait always shows itself• Recessive: gene of a trait that is hidden when the dominant gene

is present.

Mendel’s findings in modern terms• Homozygous-two alleles are the same• Ex. AA or aa

• Heterozygous-two alleles are different• Ex. Aa

• Heterozygous only dominant trait is expressed• Ex. F=freckles f=no freckles Ff=

Mendel’s findings in modern terms• Genotype-set of alleles (letters) ex. Ff• Phenotype is the physical appearance ex. Freckles

Mendel’s Ideas Give Rise to the Laws of Heredity• Law of segregation-• Alleles for a trait separate when gametes are formed.• These allele pairs are then randomly united at fertilization

(uniting of the egg and sperm to form zygote (fertilized egg)

Studying Heredity• Punnett Squares-chart that shows possible gene combinations• Organisms have at least two genes for most traits.• An uppercase letter represents a dominant trait• A lowercase letter represents a recessive trait

Mini Lab• Follow procedures found on p. 281• Answer analysis questions after completing the punnett

square problems.

Left Side• Divide page into six and define the following terms:• Homozygous, heterozygous, phenotype, genotype, dominant

and recessive• For each term complete the following: • Definition, drawing , and sentence using the term correctly (put

sentence in a box).

Acquired Traits vs. Inherited Traits• Acquired Traits are traits that you learn because of

the environment that you live in.• Example: favorite color or favorite food

• Inherited Traits are traits that are passed from generation to generation by genes inherited from your parents.• Ex. Eye color, hair color.

Non-Mendelian Patterns of Inheritance• All human traits are determined by 23 pair (46

chromosomes) of chromosomes.• 23rd pair are not alike• Males=XY• Females=XX

• The X and Y chromosome determine gender (male or female)• All eggs contain X chromosomes• Sperm cell can contain either a X or Y chromosome• Gender is inherited (determined) from the father

Sex-Linked Trait

• Sex-Linked Traits-traits that are inherited along with gender.• X chromosomes carries many genes• Y chromosome carries few genes

• Most genes for sex-linked traits are found on the X chromosome.• Sex-linked disorders are found more often in men than

women. • Most genes for sex-linked disorder is recessive• Men only have one X chromosome• If they inherit trait they will have the disorder.

Patterns of Heredity• Polygenic trait-traits that are influenced by several genes.• Ex. Hair color, skin color, weight, height, and eye color

Intermediate traits• Incomplete dominance- pattern of inheritance in which alleles

from both parents are blended.• Ex. red flower is crossed with white flower-offspring pink

flowers

Traits with two forms• Co-dominance- pattern of inheritance in which both alleles of

a gene is expressed.• Ex: Both red and white will be displayed on the flower•

Jumping Genes (Genetic Variation)• Genes that move around or jump around and relocate.• Create new genetic combinations • Only take place on certain genes (wouldn’t want your heart

genes jumping around and relocating)

DNA• Blueprint of the organism • Controls everything about the way that you look( color of your

eyes to width of your feet)• Transfers characteristics from one generation to the next

The structure of DNA• Watson and Crick determined the structure of

DNA• Three dimensional model

• DNA• Double helix-two strands twisted around each other like a winding

staircase• Each strand is made of linked nucleotides

• Made up of three parts: phosphate group, a five-carbon sugar, and a nitrogen-containing base.

• Five carbon sugar: deoxyribose

Structure of DNA.• 4 Nitrogen bases- adenine(A), guanine(G), thymine(T), and

cytosine(C)• Double helix is held together by weak hydrogen bonds • http://www.pwc.k12.nf.ca/wadey/biotech/dna1.swf

Base Pair Rule• Rule that explains how nitrogen bases pair up on the DNA

molecule• A (adenine) pairs with (T) Thymine• Guanine (G) pairs with Cytosine (C)• Build a DNA Molecule

The Replication of DNA

• Takes place in interphase• Process of making a copy of DNA

1. DNA molecule unzips between nitrogen bases2. New nitrogen bases pair up and attach to each half

of the ladder.3. Two new DNA strands that are exact copies of the

original DNA molecule

• http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf

Checking for errors• DNA polymerase: proofread role• Corrects mistakes in nucleotide bases

Left Side Assignment• Write an analogy story that relates to each step of DNA

replication. Each paragraph should relate to each step of replication.

• Step 1: something unzips• Step 2: something is added• Step 3: a copy is made• This should be written in color.

Expression of Traits

• Traits such as eye color are determined by proteins• Specific instructions are found on DNA

• Proteins are not built directly from DNA• Too large to fit through the nuclear pores

RNA • Is a special molecule that is used to make proteins• Ribonucleic Acid (RNA)

• Different from DNA in many ways• Single stranded• Has a new nitrogen base: uracil• Does not have thymine• Different sugar: ribose

From Genes to Proteins• Gene Expression

• Step one: instruction are transferred from DNA to RNA molecule in process called transcription• Step Two: Translation (takes place in

cytoplasm)-process in which cell uses two different RNA molecules to read the instructions on the RNA and put together the amino acids that make up proteins• tRNA: transfers the amino acids to the ribosome's site

of protein synthesis

The Genetic Code is Written in Three-Nucleotide “Words”• Codons-series of three-nucleotide sequences on the mRNA

(messenger RNA) that translate into the amino acids that make proteins.

• EX. AUC codes for the amino acid_______

From Genes to Proteins• SIMPLY PUT: DNA makes RNA makes Proteins make

traits( such as eye color, skin color and hair color)

Mutations• Any change in an organisms genetic material. • Can be harmful if it decreases the organism’s ability to

function properly. • Abnormalities can be detected in a karyotype.• A photo of the chromosomes

Two Types of Mutations

• Gene Mutations: result from changes in a single gene• Chromosomal Mutations: involve changes in an

entire chromosome. • Deletion- a piece of a chromosome breaks off

• Duplication-two copies of a certain set of genes

Point Mutations• Change in one or just a few nucleotides• Sickle Cell Anemia is caused by this type of mutation.

Mutations Cont.

• Mutations in gametes (egg and sperm) can be passed on from generation to generation.• Color blindness

• Mutations in body cells (somatic cells) affect only one individual.• Lung cancer

Down Syndrome (Mutation)• Caused by extra copy of 21st chromosome (non-disjunction-

when one or more chromosomes fail to separate)• Individuals with this condition• Short stature, a round face , and varying degrees of mental

retardation.

Mutations

• External influences can create mutations.• Mutations can be caused by exposure to specific

chemicals or radiation

• Example: Lung Cancer• Chemicals found in the cigarettes cause mutations

in lung cells.

• Example: Skin Cancer• Ultraviolet Rays cause mutations in skin cells.

Lung Cancer

Skin Cancer

Detecting Genetic Disorders• Most can not be cured.• Persons’ with family history may wish to undergo genetic

counseling.• Genetic Counseling- medical guidance that informs people

about genetic problems that could affect them or their offspring.

Genetic Engineering • Methods used to produce new forms of DNA.• Involves building NEW DNA by taking genes from one species and

inserting them into a completely different species.Examples of Genetically Engineered Items1. Tomatoes with elephant genes (make the tomatoes grow larger)

Benefits of Genetic Engineering

• Medicines to treat disease such as diabetes.• Identify individuals and establish relationships -DNA

fingerprinting

Benefits of Genetic Engineering• Add favorable characteristics to a plant • Resistant to pest or pesticides• Tolerate harsh environmental conditions such as drought

Benefits of Genetic Engineering

• Improve farm animals• Cows that produce more milk (more productive)• Make medically useful proteins for humans• Produce transplant organs for humans

Disadvantages • Experimenting with Bacteria can cause new diseases with no

cure.• Federal Government regulates experiments because of danger.

Questions• Create three questions and a two sentence summary for your

notes.• Make sure you write your questions next to the answer in the

notes.• Make one of your questions a How?

Snappy Products• You are a design team for a small biotechnology company.• Your Job is a follows:• 1. Brainstorm a list a ways that you can improve popcorn.• Ex. Popcorn that pops faster

• 2. Think of something else that has the desired trait that you want to see in your popcorn.

• 3. Combine the solution that you thought of in #2 with popcorn, make the “the popcorn” that can solve the problem that you mentioned in #1.

• Assignment: Draw your new popcorn product, be sure to clearly show what other product that you combined with your popcorn to create something new.

• Create a catchy name for you product• Write a tune with words to be used to as a radio commercial.

Include your price in your song.