Lecture 5: Mendel and Basic Genetics

Question 1

blending inheritance

Answer 1

-gametes contained genes that blended when the gamet fused

Question 2

why did Mendel work with peas?

Answer 2

• small, easy to grow, very short generation time

- therefore easy to get a lot of data on them very quickly

Question 3

true breeding

Answer 3

• a plant that when they reproduce, all the offspring look like the parents
• he focused on flower color trait

Question 4

monohybrid cross

Answer 4

-causes btwn 2 individuals that only differ in terms of a single trait

Question 5

trait

Answer 5

• a specific form of a character

- ex: eye color is a character, brown eyes are a trait)

Question 6

hybrid

Answer 6

-the offspring of crosses btwn organisms differing in one or more characters

Question 7

p generation

Answer 7

• parental generation

- the first two individuals that mate in a genetic cross

Question 8

F1 generation

Answer 8

-the first generation of offspring obtained from an experimental cross of two organisms

Question 9

F2 generation

Answer 9

-offspring of the F1 generation

Question 10

cross fertilization

Answer 10

• aka pollination
• process by which sperm from one flower’s pollen fertilizes the eggs in a flower’s pollen fertilzes the eggs in a flower of a different plant

Question 11

self crossing

Answer 11

-pollen with fertilize an egg from the same plant

Question 12

latent trait

Answer 12

-present but unseen traits (like carriers)

Question 13

gene

Answer 13

-the unit of genetiv function which carries the information which carries the information for a polypeptife of RNA

Question 14

allele

Answer 14

-the alternate form of a genetic character found at locus of a chromosome

Question 15

homozygous

Answer 15

-an organism that has two alleles that are the same

Question 16

heterozygous

Answer 16

-an organism that has two different alleles

Question 17

phenotype

Answer 17

-the physical appearance of an organism resulting from both genetic and environmental factors

Question 18

genotype

Answer 18

-the genetic constitution og an individual, either with respect to a single trait or with respect to a larger set of traits

Question 19

law of segregation

Answer 19

• two alleles segregate during gamete formation to be rejoined at random during formation
• allows for the expression of latent traits in heterozygous parents

Question 20

what is the phenotype and genotype ratios in a one gene punnett square?

Answer 20

• phenotype: 3:1

- genotype: 1:2:1

Question 21

what is the phenotype ratio in a dihybrid cross?

Answer 21

• 9:3:3:1

- in F2 generations

Question 22

the principle of independent assortment

Answer 22

-in a dihybrid cross the alleles of each gene assort independently

Question 23

do genes always assort independently?

Answer 23

• no, they’re sometimes linked

- sometimes certain traits that belong to a given alleles almost always appear together

Question 24

what does it mean to “cross” something?

Answer 24

-to breed

Question 25

the meaning of the five element model: what conclusions does Mendel draw from each of his elements?

Answer 25

- parents give information to offspring - each offspring gets 2 copies of each factor - not all factors are the same and different combinations lead to different traits - alleles don't blend - presence of a factor doesn't guarantee it'll be expressed

Question 26

dihybrid crosses

Answer 26

-double heterozygous trait

Question 27

two state cases vs. multi-state cases

Answer 27

- two state: cases of either/or - multi-state: more than one thing affects genes; addictively affect inheritance (ex: some alleles add height, some don't)

Question 28

polygenic inheritance

Answer 28

-the heredity of complex characters that are determined by a large number of genes, each one usually having a realitvely small effect

Question 29

epistasis

Answer 29

- an allele of one gene modifies or prevents the expression of alleles at another gene - ->ex: one locus determines the color of the flower, however, the other locus determines the color of the flower

Question 30

how is epistasis different from polygenic inheritance?

Answer 30

- epistasis is when an allele of one gene modifies or prevents the expression of alleles at another gene - polygenic inheritance is when multiple genes affect a phenotype

Question 31

given a genotype, would you know what color a labrador was?

Answer 31

- yes if given what alleles were dominant and recessive - ee = yellow lab - E_bb = brown lab - E_B_ = black lab

Question 32

pleiotropy

Answer 32

- aka multiple effect | - 1 gene = many traits/trait outcomes

Question 33

why is sickle cell still around?

Answer 33

- sickle cell anemia > malaria > immune | - malaria = immune

Question 34

incomplete domniance

Answer 34

-the heterozygous phenotype is intermediate btwn the two homozygous phenotypes; neither of the 2 alleles is dominant

Question 35

codominance

Answer 35

-a condition in which two alleles at a locus produce different phenotypic effects and both effects appear in heterozygotes

Question 36

how does incomplete dominance differ from codominance? could you tell them apart?

Answer 36

- in incomplete dominance, the phenotype resembles a sort of bleding of the two alleles (red and white pedals blended make pink petals) - codominance is when both alleles are expressed separately(red and white pedals blended make a flower with white and red splotches)

Question 37

environmental effects on gene expression

Answer 37

- huge impact on genes | - darker fur on extremeties and head due to the less blood flow/lower temperature, but white fur close to body

Question 38

how are blood types determined?

Answer 38

-based on what parent's blood types are and what results of codominance

Question 39

the importance of quantification of results

Answer 39

-mathematical to see traits would show in ratios

Question 40

gregor mendel and his work

Answer 40

- focused on how traits were passed down - wanted all offspring to look alike - crossed 1 true bred & created a hybrid, then crossed hybrids

Question 41

gamete

Answer 41

- sex cells that contain sets of chromosomes | - 2 come together to form new life