DAT bio Chapter 7. Heredity

Question 1

Genome

Answer 1

• all the DNA within a cell.

Question 2

Gene

Answer 2

• sequence of DNA that codes for a trait.

Question 3

locus

Answer 3

• location of a gene on a chromosome.

Plural is gene loci

Question 4

allele

Answer 4

one variation of a gene

Question 5

wild type allele

Answer 5

normal allele that is most
common in nature. Can turn into a mutant
allele

Question 6

mutation

Answer 6

• heritable change in DNA

Question 7

Genotype

Answer 7

Set of genes responsible for trait
Ex BB Bb bb

BB is brown eyes
Bb is blue eyes

Question 8

Phenotype

Answer 8

observable traits that result from

a genotype.

Question 9

Dominant alleles

Answer 9

• mask the expression of
  recessive alleles. Typically represented by
  uppercase letters (“A”)

Question 10

Recessive alleles -

Answer 10

• only show up in a
  phenotype if dominant alleles are not present.
  Typically represented by lowercase letters (“a”).

Question 11

Homologous pairs

Answer 11

two pieces of DNA within a diploid organism which carry the same genes, one from each parental source. In simpler terms, both of your parents provide a complete genome. Each parent provides the same 23 chromosomes, which encode the same genes

Question 12

Heterozygous -

Answer 12

one dominant allele and one

recessive allele in its homologous pair

Question 13

Homozygous -

Answer 13

• same allele in both homologs.
  Can be homozygous dominant or
  homozygous recessive.

Question 14

Hemizygous

Answer 14

only one allele is present. For
example, men only have one X and one Y
chromosome (not homologous), which contain
hemizygous genes

Question 15

Penetrance -

Answer 15

proportion of individuals who exhibit the phenotype of an allele for a given gene. Can be complete penetrance or
incomplete penetrance. As shown below, Bb
individuals all have brown eyes only when
there is complete penetrance (refers to the probability of a gene or trait being expressed. )

Question 16

Expressivity

Answer 16

describes how well a certain phenotype is expressed? All of the
children of this couple have genotype Hh for
medium thick hair, but because of expressivity,
just how medium thick (or medium thin) the
hair is varies. (degree of how expressed one phenotype is)

Question 17

Incomplete dominance

Answer 17

The dominant allele is not fully expressed when the recessive allele is around. will have an intermediate state. (Ex.
red x white = pink).

Question 18

Codominance

Answer 18

heterozygous genotype
expresses both alleles. (Ex. red x white = red +
white spots).

Question 19

Multiple alleles

Answer 19

n there are more
allele options than just two. (Ex. ABO blood typing
- A, B, O alleles)

Question 20

Epistasis

Answer 20

One gene suppresses the expression of another gene
Ex. baldness gene covers up
the genes for hair color)

Question 21

Pleiotropy

Answer 21

describes when one gene is
responsible for many traits. (Ex. cystic fibrosis is a
disease with many symptoms caused by a single
gene).

Question 22

Polygenic inheritance

Answer 22

many genes are
responsible for one trait. This gives the trait
continuous variation. (Ex. height, a single trait
affected by many genes

Question 23

Haploinsufficiency

Answer 23

when one copy of the
gene is lost or nonfunctional and the expression of
the remaining copy is not sufficient enough to
result in a normal phenotype. It can result in an
intermediate phenotype.

Question 24

Haplosufficiency

Answer 24

describes when the remaining
copy of the gene is sufficient enough to result in a
normal phenotyp

Question 25

Proto-oncogenes

Answer 25

e genes that can become
oncogenes (cancer-causing genes) due to
gain-of-function mutations. Gain-of-function
mutations can cause too much protein to be
made or production of an over-active protein;
Cancerous growth occurs as a result.
Proto-oncogenes are normally involved in cell cycle
contro

Question 26

one hit hypothesis

Answer 26

states that a gain-of-function mutation in

one copy of the gene turns it into an oncogene. This is associated with proto oncogenes

Question 27

Tumor-suppressor genes

Answer 27

(Anti oncogenes) genes that become
cancerous as a result of loss-of-function
mutations, because they are normally needed to
suppress cancerous growth

Question 28

two hit

hypothesis

Answer 28

states that a loss-of-function
mutation in both copies of the gene are needed to
make it cause cancer. Thus, tumor-suppressor
genes are haplosufficient. This is associated with tuomr suppressor genes

Question 29

Null alleles

Answer 29

come from mutations that cause the
alleles to lack normal function. Tumor-suppressor
genes have null alleles when they become
cancer-causing

Question 30

p53

Answer 30

important tumor-suppressor gene
that is known as the guardian of the cell . It is
upregulated (increase its response to a substance) to prevent cells from becoming
cancerous.

Question 31

p21

Answer 31

s another tumor-suppressor gene that
inhibits phosphorylation activity in order to
decrease rampant cell division.

Question 32

Retinoblastoma gene (RB)

Answer 32

is a
tumor-suppressor gene that codes for a
retinoblastoma protein, which prevents
excessive cell growth during interphase

Question 33

Gregor mendel proposed three laws

Answer 33

laws of dominance
law of segregation
law of independent assortment

Question 34

laws of dominance

Answer 34

dominant alleles mask
the expression of recessive alleles. Mendel
studied plant height to come to this conclusion.

Question 35

Law of segregation

Answer 35

homologous gene copies
separate during meiosis (specifically anaphase
I). Thus, Aa individuals will produce gametes
with “A” or “a” alleles

Question 36

homologous gene copies
separate during meiosis (specifically anaphase
I). Thus, Aa individuals will produce gametes
with “A” or “a” alleles

Answer 36

homologous chromosomes line up
independently during metaphase I of meiosis
so that alleles separate randomly (this
increases genetic variability). Metaphase II is
different, during which sister chromatids are
pulled apart instead. The law of independent
assortment can produce 2

23 options (23
homologous chromosome pairs split).