Bio Chapter 7 Genetics

Front 1

Griffith Experiment

Back 1

1.) First he injected the mouse with the live S strain of Streptococcus pneumoniae. The mouse died

2.) Then he injected with the R strain that lacked the polysaccharide capsule. The mouse survived.

3.) Then he injected with heat killed S strain. The mouse survived

4.) Then he injected with heat killed S strain and R strain. The mouse died

This shows that the S strain somehow transferred something to R strain that made R strain become deadly

Front 2

Avery-MacLeod-McCarty Experiment

Back 2

They took the S strain and systematically destroyed each macromolecule in the S strain to see which one if removed causes the mouse to survive. When DNA was removed the mouse survived

Front 3

Hershey-Chase experiment

Back 3

Used T2 virus.

One culture of phages contained radioactive phosphorus which labeled the DNA and one culture used radioactive sulfur which labeled the capsid protein.

The radioactive DNA was found in the bacterial cells. This shows that DNA was the hereditary material

Front 4

autosome

Back 4

non sex chromosome

Front 5

homologous chromosomes

Back 5

2 nonidentical copies of a particular chromosome. The chromosomes are nonidentical because although they code for the same type of genes, they may have different alleles

The chromosomes in a chromosome pair are homologous chromosomes

Front 6

alleles

Back 6

Different versions of the same gene

Front 7

genotype

Back 7

DNA sequence of alleles a person carries

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Heterozygote

Back 8

individual that has two different alleles

Front 9

homozygote

Back 9

individual that has the same alleles

Front 10

phenotype

Back 10

physical expression of the genes

Front 11

What do homologous chromosomes do during prophase 1 of meiosis?

Back 11

they align with each other to form a bivalent or tetrad

Front 12

What happens after the tetrad is formed?

Back 12

crossing over or recombination

This leads to genetic variation

Front 13

Synaptonemal Complex

Back 13

Contains proteins SYCP2, SYCP3, SYCP1

SYCP2 and SYCP3 attach to each of the homologous chromosome pairs. This makes up the lateral elements of the complex

The lateral elements then align and attach at a central region made of SYCP1

the complex works like a zipper to connect the chromosomes

Front 14

metaphase 1 of meiosis

Back 14

The tetrads align at the center of the cell

Front 15

Anaphase 1 of meiosis

Back 15

homologous chromosomes separate but sister chromatids stay together

Front 16

Telophase 1 of meiosis

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the cells divides

Nuclear envelope DOES NOT REFORM

the two daughter cells are now haploid because they contain only a single set of chromosomes and no longer homologous pairs

Front 17

Prophase II of Meiosis

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Nuclear envelope or chromosome ceondensing does not occur.

Instead, only spindle fibers need to form

Front 18

nondisjunction

Back 18

failure of chromosomes to separate correctly during anaphase 1 or 2

Front 19

test cross

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when one individual is crossed to another individual that has homozygous recessive genotype

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law of segregation

Back 20

two alleles of an individual are separated and passed onto the next generation singly

Front 21

law of independent assortment

Back 21

alleles of one gene will separate into gametes independently of alleles of another gene

Front 22

Incomplete Dominance

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causes the phenotype of a heterozygote to be a blended mix of the two alleles

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Codominance

Back 23

both alleles are expressed and not blended

Front 24

Rule of mutiplication

Back 24

can be used to find the probability of two events happening together

(probability of A * probability of B)

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Rule of addition

Back 25

probability of events occurring separately

(probability of A + probability of B) - (probability of A * probability of B)

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Pleiotropism

Back 26

a gene is pleiotopic if it alters many different, seemingly unrelated aspects of an organisms phenotype

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Polygenism

Back 27

Complex traits that are influenced by many genes

Front 28

Penetrance

Back 28

chance of expression of genotype

(always given in percentage)

Front 29

Epistasis

Back 29

expression of alleles for one gene is dependent on a different gene

Front 30

What gamete determines the gender of the embryo?

Back 30

the male gamete

Front 31

Linkage

Back 31

failure of genes to display independent assortment because they are located on the same chromosome

Front 32

Why are chromosomes in Meiosis homologous and not identical?

Back 32

due to recombination

Front 33

Trigger word for MITOSIS on MCAT

Back 33

Identical

Front 34

Trigger Word for MEIOSIS on MCAT

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homologous

Front 35

What does nondisjunction ALWAYS lead to?

Back 35

Results in a complete chromosomal addition

(TRISOMY) And a complete chromosomal deletion (Monosomy)

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Why are there no autosomal monsomies known?

Back 36

because they are Lethal

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Kleinfelters syndrome

Back 37

XXY

Front 38

Where are genes located?

Back 38

on their particular Locus

Front 39

Classical Dominance

Back 39

Given two alleles, the dominant one is expressed

Front 40

When solving genetic questions using rule of multiplication or addition, use a punnet square to solve for the chance of phenotype or genotype for each particular gene. Then multiply or add these probabilities together

Back 40

Example: HhEe and HhEe cross

Do punnet square for the H gene. Do punnet square for the E gene. Then multiply the probabilities needed based on the question

Front 41

Normal Unlinked phenotypic ratios of:

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Double heterozygous crossed with double heterozygous- 9:3:3:1

Double hetero crossed with double homo recessive- 1:1:1:1

Deviation from any of this shows that genes are linked

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Does the chance of independent assortment increase if linked genes are farther apart?

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yes due to higher chance of recombination occurring between them

Front 43

Frequency of recombination

Back 43

determines a unit distance between linked genes

Higher frequency means genes are farther apart

Front 44

Frequency of recombination equation

Back 44

(Number of recombinant phenotypes) / (Number of total progeny)

Front 45

How to determine the recombinant phenotypes?

Back 45

Recombinant phenotypes are the phenotypes different than the parents

Front 46

Population Genetics

Back 46

study of alleles in a population over time

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Hardy-Weinberg Theory

Back 47

the frequency of alleles in a population does not change over time

Front 48

frequency of alleles

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number of specific alleles/ total alleles

Front 49

Five assumptions of Hardy Weinberg Theory

(assumptions are impossible to occur so theory is retarded)

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1.) No mutation

2.) No migration

3.) Random mating

4.) No natural selection

5.) Population is large / No genetic Drift

Front 50

Equilibrium is reached after one generation

Back 50

YUh

Front 51

Both Hardy Weinberg Equations

Back 51

1.) P + q = 1

2.) P^2 + 2pq + q^2 = 1

P= frequency of dominant allele (single allele)

q= frequency of recessive allele (single allele)

P^2 = Frequency of Homozygous dominant

2pq= Frequency of heterozygous

q^2= frequency of homozygous recessive