Intro to Genetics

CATALYST1. Which traits

do you think come from your DNA? Why?

2. Which traits do you think come from your environment? Why?

Brown eyesFast RunnerBlue eyes

Normal VisionNear Sightedness

Dark hairHardworkingStraight HairWidow’s peak

DimplesAttached earlobes

Freckles Pierced Ears

AllergiesTongue-rolling

GREGOR MENDEL

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http://science.discovery.com/videos/100-greatest-discoveries-shorts-genetics.html

What do you

know?

What is a gene?

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GREGOR MENDEL

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You inherit2copies of every gene, one

from eachPARENT

gamete

Each copy is called anALLELE

In most cases, each gene has a

DOMINANT &RECESSIVE

allele possibility

GREGOR MENDEL

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These alleles (GENES)

determine what proteins get

made/expressed (TRAITS)

Gene alleles are inherited

INDEPENDENTLY of other

genes.

Example: Just because you

inherited Brown hair, does not mean you will

have brown eyes

VOCABULARYGENOTYPE

VS. PHENOTYPE

Genotype: the genes that make up your body; the “type of genes” you have

Example: AA, Aa, aa, RR, Rr, rr

Phenotype: what we look like; our physical appearanceExample: Brown hair, blue eyes, tall height

VOCABULARY

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Brown hair.

VOCABULARY

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Bb.

VOCABULARY

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Small hands.

VOCABULARY

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ss

DOMINANT VS. RECESSIVEGenes are what you INHERIT from each PARENT. Every gene will have two forms or alleles, DOMINANT or RECESSIVE.

DOMINANT: the allele that shows up, or can be seen is dominant. STRONGWritten as: CAPITAL LETTERS Example: R, S, T, Q, M, N, D

RECESSIVE: the allele that is seen only when both alleles are recessive. WEAK.Written as: LOWER-CASE LETTERS Example: r, s, t, q, m, n, d•If the trait for “big nose” is the dominant trait, use “B” to represent the dominant allele.

•If the trait “small nose” is the recessive trait, use “b” to represent the recessive allele.

Don’t change the LETTER, just the capitalization!!!!

•Only 1 dominant allele must be inherited for the dominant trait to be expressed (show up)Example: BB or Bb

•2 recessive alleles must be inherited for a recessive trait to be expressed (show up)Example: bb

NN = __________________ Nn= __________________ nn= __________________

DOMINANT DOMINANT RECESSIVE

DOMINANT VS. RECESSIVE

VOCABULARY

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GENOTYPEVS.

PHENOTYPE

VOCABULARY

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Dominant or Recessive?

T

VOCABULARY

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Dominant or Recessive?

k

VOCABULARY

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Dominant or Recessive?

L

HOMOZYGOUS VS. HETEROZYGOUS

HOMOZYGOUS: both letters (alleles) are the SAME• HOMO- : same• Example: BB, RR, mm, LL, hh, TT, dd

HETEROZYGOUS: each letter is DIFFERENT or MIXED• HETERO- : different or mixed• Example: Hh, Bb, Rr, Tt, Ll, Kk Ss, Gg

There are 3 combinations of alleles (genotypes):

1. Homozygous Dominant (DD) Phenotype = Dominant2. Heterozygous (Dd)Phenotype = Dominant3. Homozygous Recessive (dd) Phenotype = Recessive

Additional Terms:

Homozygous= True/Pure Breeding

Heterozygous = Hybrid

VOCABULARY

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HeterozygousHomozygous

DominantHomozygous

Recessive

VOCABULARY

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HH

VOCABULARY

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Dd

VOCABULARY

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dd

VOCABULARY

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Oo

GREEN

GREEN

YELLOW

HOMOZYGOUS DOMINANTHOMOZYGOUS RECESSIVEHETEROZYGOUS

TT

Tt

tt SHORT

TALL

TALL HOMOZYGOUS DOMINANT

HOMOZYGOUS RECESSIVE

HETEROZYGOUS

T

t

___ :Wrinkled

___: Smooth

W

w

WW

Ww

ww

WRINKLED

WRINKLED

SMOOTH

HOMOZYGOUS DOMINANT

HETEROZYGOUS

HOMOZYGOUS RECESSIVE

HD

HE

HE

HE

HR

HE

HE

HE

HR

HE

HR

HR

PURPLE

PURPLE

WHITE

BROWN

BROWN

BLUE

ROUND

ROUND

WRINKLED

LONGTAIL

LONGTAIL

BOBTAIL

SS

Ss

ss

PP

Pp

pp

Small EyesNormal TeethFreckles

Gentoype = Tt (Heterozygous)Phenotype = Normal Teeth

Gentoype = ff (Homozygous

Recessive)Phenotype = Freckles