Lesson 2

Question 1

what did Darwin not know?

Answer 1

that DNA played a role in inheritance or of its existance

Question 2

what were the theories of inheritance in the mid 1800s?

Answer 2

blending inherence and inheritance of acquired traits

Question 3

what is blending inheritance theory?

Answer 3

offspring have traits that are intermediate to their parents

Question 4

what’s Lamarck’s inheritance of acquired traits theory?

Answer 4

favorable traits acquired by parents are passed on to offspring (direct evolution)

Question 5

if blending inheritance was the mechanism of inheritance what would happen to variation over time?

Answer 5

reduction

Question 6

why is blending inheritance theory wrong?

Answer 6

variations aren’t reduced over time and it doesn’t reflect the constant presence of variation observed in populations

Question 7

who is Gregor Mendel and what did he find?

Answer 7

tested hypothesis of blending vs particular inheritance, used true-breeding varieties of peas, many varieties with different characters, 1822-1884, published versuche uber pflanzenhybriden (experiments on plant hyperdization) in 1866, not translated into English till 1901

Question 8

what is “true breeding” varieeties?

Answer 8

always give the same phenotype when self-crossed

Question 9

what was the objective in Gregor mandels expe9irnments?

Answer 9

determine whether statistical patterns in the occurrence of contrasting traits persisted by means of crossing

Question 10

what were the important distinctions of Gregor mendals experiments?

Answer 10

true breeding strain (homozygous)
focused on a single trait at a time
quantitative counted the progeny

Question 11

what is usually the interaction of dom and rec genes w proteins?

Answer 11

dom code for a functional protein and recessive does not

Question 12

what happened to the pea plants which crossed (P0) parental generation homo dom and homo rec?

Answer 12

got (F1) first filial generation (always heterozygous ands showing dominate trait) with yellow seeds (dom) not green seeds (rec)

Question 13

what determines the pea color and how does the alleles play into it?

Answer 13

pea color determined by presence of a functional enzyme that breaks down chlorophyll
AA and Aa have large percent of chlorophyll breakdown due to coding for this enzyme while aa does not, causing green pigment

Question 14

what occurs in segregation single character (monohybrid) cross?

Answer 14

P generation (parental) cross 2 true breeding varieties with a different phenotype
F1 generation seeds which the self fertilize
F2 generation seeds show 3:1 phenotypic ratio (dom:rec) and 1:2:1 genotypic ratio PROBABILITY NOT GAUREENTED OUTCOME

Question 15

what is Mendel’s principle of segregation?

Answer 15

each organism is diploid, has two alleles, first person to say this, that we get one from each parent

Question 16

what’s homozygous mean?

Answer 16

2 allele are the same therefor produce only one type of gamete

Question 17

what’s heterozygous mean?

Answer 17

2 alleles are different therefor produces two types of gametes

Question 18

pea seeds in the F2 generation showing green phenotype must be?

Answer 18

homozygous recessive a/a

Question 19

how would you differentiate between A/A and A/a genotypes?

Answer 19

distinguish by the seeds produced when F1 is self fertilized

Question 20

how would you determine if you have a heterozygote?

Answer 20

test cross

Question 21

what’s a test cross?

Answer 21

mating indv w dom phenotype to an indv w homozygoud recessive genotype, shows if tester carrie3s recessive allele

Question 22

what are the results of the test cross if heterozygous?

Answer 22

1:1 dom and rec phenotypes

Question 23

what are the results of the test cross if homozygou8s?

Answer 23

all dom phenotype

Question 24

what was Mendel’s hypotheses?

Answer 24

adult plants carry two copies of factors (genes) that govern the inheritance of a character
if indv pair of genes consist of diff alleles, one allele is dominant over the other (masks recessive)
the pair of alleles that control a character separate as gametes (meiosis) half carry one allele and other carry other allele (Mendel’s principle of segregation)
diploid organisms get one allele from each parent

Question 25

What’s a mono hybrid cross?

Answer 25

A cross between two heterozygous (for a single gene)

Question 26

What’s the probability of a gamete inheriting one of the 2 alleles? Genotype?

Answer 26

During meiosis random bc of random alignment of chiromosomes at metaphase plate Probability of genotype in a cross is determined by the product of the probabilities of acquiring each gamete from the mother and father

Question 27

When should you use the product rule?

Answer 27

Probability of two independent events occurring in succession, indv probabilties are multiplied

Question 28

When do you use the sum rule?

Answer 28

Probability of an outcome that can be achieved by two or more mutually exclusive

Question 29

In a heterozygous self cross what’s the probability of a P/P zygote? p/P zygote? P/p? p/P? Heterozygote?

Answer 29

1/2 x 1/2 = 1/4 1/2 x 1/2 = 1/4 1/2 x 1/2 = 1/4 1/2 x 1/2 = 1/4 1/4 + 1/4 = 1/2

Question 30

What did Walter Sutton find?

Answer 30

1903, chromosomes occur in pairs in diploid organisms, each pair separated in gamates, separation of chromosome is independent of other pairs Found chromosomal theory of inheritance

Question 31

In simple Mendelian inheritance what happens with dominant and recessive traits?

Answer 31

Dominant traits always mask recessive ones

Question 32

What’s incomplete dominance?

Answer 32

Intermediate phenotype, one allele is not complete dominant to the other allele, use a superscript to label alleles

Question 33

What’s codominance?

Answer 33

Both traits expressed, alleles have equal effects (heterozygoyes exhibit both homozygous phenotypes)

Question 34

How did Mendelian segregation solve Darwin’s conundrum?

Answer 34

the inability to explain how favorable traits persist rather than blending away—by proving that inheritance is particulate rather than blending. By demonstrating that traits are passed down as distinct, stable units (genes) that separate during reproduction, Mendel showed that beneficial variations are preserved over generations

Question 35

What’s polymorphic/polyallelic/multi-allelic?

Answer 35

Have multiple alleles for a given gene

Question 36

What’s a polymorphic gene?

Answer 36

MHC cell surface molec controlling part of immune system, two alleles of each MHC gene expressed codominantly, someMCH genes highly polymorphic (1000+ alleles), highly unlikely for two indv to carry the exact two alleles for MHC gene

Question 37

What’s a discrete trait characteristics?

Answer 37

Aka Mendelian One gene two alleles Phenotype is consistent for genotype, Complete incomplete or co-dominance

Question 38

What are complex trait characteristics?

Answer 38

Multiple genes, multiple alleles Variations in phenotype with same genotype

Question 39

What are the benefits/consequence of polygenic traits?

Answer 39

More genes = more complexity in phenotypes “smoother” distribution