Lecture 8: Classical, Modern, and Human Genetics

Question 1

What did Gregor Mendel do?

Answer 1

studied heredity in pea plants (mainly texture and color of seeds; based solely on observation (no knowledge of DNA or meiosis)

Question 2

Life span of Gregor Mendel??

Answer 2

1822-1884

Question 3

Law of Segregation

Answer 3

There are 2 sets of genes for a particular trait (one from each parent), but only one gets into gamete during gametogenesis

Question 4

Law of Independent Assortment

Answer 4

During gametogenesis, a gene that enters a gamete does so independently of those for other traits (ex: red hair expressed, blue eyes not necessarily expressed)

Question 5

Alleles

Answer 5

Different forms of same gene (found at same locus)

Question 6

Dominant Allele

Answer 6

Form expressed in offspring (if present)

Question 7

Recessive allele

Answer 7

Masked by dominant Allele (not expressed if dominant Allele present), but can still be passed onto next generation (by a carrier)

Question 8

Phenotype

Answer 8

description of form of physical trait an individual
exhibits (ex. trait of hair color, “red hair” is a phenotype)

Question 9

Genotype

Answer 9

description of individual’s condition at the genetic
level; three possible genotypes:

Question 10

Homozygous Dominant

Answer 10

AA: both genes for trait instruct to produce
dominant phenotype

Question 11

Homozygous recessive

Answer 11

AA: both genes for trait instruct to produce
recessive phenotype

Question 12

Heterozygous

Answer 12

Aa: genetic instructions conflict; for Mendelian traits,
dominant phenotype results (recessive masked)

Question 13

Mendel described traits in __________________ and __________________

Answer 13

P (parental generation), F1
and F2 (filial) generations

Question 14

Monohybrid Cross

Answer 14

single trait; parents’ genotypes crossed using
Punnett Square

Question 15

Dihybrid Cross

Answer 15

two traits; find results for each single trait with
Punnett Square, then multiply probabilities (ex. ¼ X ¼ = 1/16)

Question 16

Polygenic traits

Answer 16

traits caused by multiple genes

Question 17

Variation in population often follows ________ when frequency is
plotted against measurement of phenotype (ex. height)

Answer 17

bell curve

Question 18

Multiple Alleles + example

Answer 18

Only two alleles in any cell, but more than 2 in population (ex: blood types)

Question 19

Linked genes

Answer 19

Loci typically in close proximity

Question 20

Incomplete Dominance or Co-Dominance

Answer 20

Phenotype for heterozygous genotype is a mixture (blend) of
those caused by homozygous genotypes

Question 21

Sex Determination

Answer 21

23rd pair of human chromosomes are the sex chromosomes, others are
autosomes

Question 22

Chromosomes for Females

Answer 22

XX

Question 23

Chromosomes for Males

Answer 23

XY

Question 24

Sex linked traits

Answer 24

X-sex chromosome has many
genes other than those for sex determination,
but Y-sex chromosome does not → no male
carriers for sex-linked traits

Question 25

Examples of sex-linked traits

Answer 25

Color blindness, hemophilia