Genetics

BUILDING BLOCKS….

A CELL is the building block of all living things!

/CELL THEORY:

* All living things are made of cells Hooke* Cells are the basic units of structure and

function of an organisms*Living cells come from other living cellsSchleiden Schwann Virchow

Some organisms are only 1 (one) cell big or UNICELLULAR!

Some organisms have many cells or are MULTICELLULAR!

•DNA is a long - Double helix

strand which stores our

genetic code

• There are 4 base pairs

•A – T

•C - G

DNA, DNA….where are you?

I’m inside the NUCLEUS OF THE

CELL!

What is a Gene?

Genes are made up of DNA

Genes are instruction manuals

for our bodies.

Base pairs = Letters

Genes = Words

DNA = Book

Think of an alphabet….

Different organisms have different #’s of chromosomes

Humans have

46

Mosquitoes

have 6

Onions have

16

“So do I!” “Let me write a song about us…I love

your 46 chromosomes,

la la la”

“I have 46 chromosomes

…. yeah yeah…”

SPERM

EGG

WHY? (Answer on your notes)

THESE CELLS ONLY HAVE 23 CHROMOSOMES.

2 of those 46 chromosomes determine whether you are a male or a female.

They are called sex chromosomes

(represented by X and Y).

XX = female XY = male

Karyotype

The cell drawing

New terms to study

• New terms:– Unicellular– Multicellular– Chromosomes– Body cell – 46 chromosomes– Sex cells – 23 chromosomes– Cell membrane– Nuclear membrane– Nucleus

Gregor Mendel – Father of Genetics

GREGOR MENDEL FATHER OF GENETICS

•Worked as a MONK and loves Pea plants•Observable TRAITS•Tall pea plant with a short pea plant I got all TALL pea plants

How are genetic traits determined?

Example:

We have two (1 from mom and 1 from dad) alleles for each gene.

1 2 1 2 1 2 1 2

HH Hh hH hh

Homozygous or “true” means two of the same alleles. HH ….. Straight

hh ….. Hitchhikers

Heterozygous or “hybrid means two different alleles.

1 2 1 2 1 2 1 2

HH Hh hH hh

Ex. Hh

Bb

aa

Cc R

R

QQ ZzzZ

Heterozygous or Homozygous?

“But what happens when you have two different alleles? Hh?”

What will Hh look like?

There are dominant and recessive alleles

Dominant alleles

capitol letter

T = tall plant

Recessive alleles

lowercase letter

t = short plant

The “stronger” dominant allele masks the “weaker” recessive allele.

HH = (the dominant allele will be shown)

Hh = (the dominant H allele masks the recessive h allele)

hh = (the recessive alleles can come through

Results

The physical appearance of the organism is called the

Phenotype .

The genetic makeup of an organism is called the

Genotype .

Hh

WRITE THESE DEFINITIONS ON THE BOTTOM OF YOUR NOTE SHEET

Meet Mama and Papa Bear

Mama Papa

Mama bear is homozygous dominant for the claw gene.

Papa bear is homozygous recessive

for the claw gene.

The Claw gene (C)

Phenotype: has claws

Genotype: CC

Genotype: ccPhenotype: no claws

CC

cc

Step Two:

Step Three:

Meet Baby bear!Phenotype: has

claws

Cc C

c

Cc

Cc

Cc

Cc

Cc

A male rat has a dominant gene for fur color, which is brown. (We will show the homozygous dominant gene as BB.) A female rat has the homozygous recessive gene for fur color, which is gray. (we will show this heterozygous recessive gene by the letters bb.) What will the genotype of the offspring look like?

Fur Color (B)

Mom has Straight Thumb

(Tt)

Hitchhikers Thumb(H)

Dad has Hitchhikers Thumb

(tt)

Green Pod color (Yy)

Pea Pod Color (Y)

Yellow Pod color (Yy)

Oh good. Peas!

Mom is Heterozygous

with Free earlobes

Earlobes (E)

Dad is Homozygous Recessive

with attached earlobes

In pea plants, tall pea plants (T) are dominant over short pea plants (t). Construct a Punnett

Square for a heterozygous tall pea plant and a short pea plant.

Tt tt

Tt tt

T t

t

t

What are the percentage of phenotypes?

50% tall

50% short

Pea Plant Height (T)

A _____Pedigree______ is a “family tree” that tracks which family members have a trait.

What is a Pedigree?

We use the following symbols to represent family members on pedigrees

Marge Homer

Bart Lisa Maggie

Marge has long eyelashes (EE)

Homer does not (ee)

We designed a pedigree for the Simpsons investigating the trait of long eyelashes.

Long eyelashes (E) are dominant to short eyelashes (e).

Let’s fill in the family members affected with the long eyelash gene.

(E)- Long eyelashes (e)- short eyelashes

Marge Homer

Bart Lisa Maggie

What if Maggie were to get married?

What if Maggie and her husband had

three kids?

What if Maggie’s first child got married?

Trait (R)

Mother is _____________

Father is _____________

Son is _____________

Daughter is _____________

Trait (H)

Mother is _____________

Father is _____________

Son is _____________

Daughter is _____________

1

10

12 14

DNA vs. RNA

DNA:• Double helix•Stays in/found in Nucleus•Genetic information to make you

RNA:• Single stranded•Moves out of nucleus•Carries the recipe (information) to make proteins

BOTH: • Made up of 4 bases

•Contain genetic information•Nucleic Acids

BASIC STEPS TO MAKING PROTEIN

1) DNA is found inside the Nucleus of our cells.

2) DNA makes a single stranded copy of itself. This is called RNA.3) RNA is similar to DNA, containing 4 base pairs, with one different letter (U instead of T)4) This RNA moves out of the nucleus (called messenger RNA or mRNA) 5) mRNA travels to the RIBOSOMES (an organelle in the cell that makes proteins)6) The RIBOSOMES read the recipe that mRNA is carrying. 7) The recipe has the information to bring in specific AMINO ACIDS to build the needed protein. 8) When the RIBOSOME reads “stop” on the recipe (mRNA). The amino acids fold together to make the protein. The protein moves to the needed area in the body.

Mitosis – I P on a MAT

5 stages:1) Interphase – resting phase

2) Prophase – DNA makes a copy

3) Metaphase – Chromosomes line up in center

4) Anaphase – Chromatids separate and move to opposite ends of cell

5) Telophase – Nucleus reappears and cell begins to divide.

How many chromosomes are found in each new cell?

MEIOSIS – division of sperm and egg cells

Similar steps as in Mitosis, however, the end result is each cell has 23 Chromosomes. •Why do these cells have half the number of chromosomes as body cells?

•23 +23 = 46•What does the 23rd pair of chromosomes determine?

•gender•A boy – XY A girl - XX

An ALLELE is a version of a gene.

We give each gene a letter …either lowercase or capitol

Example: Gene controlling thumb shape = the letter H

Straight Thumb allele = H .

Hitchhicker’s Thumb allele= h .

RW RW

RW RW

R R

W

W

AB BO

AO OO

A O

B

O

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2.