ch 7- heredity

Question 1

locus

Answer 1

locaition of a gene on a chromosome

Question 2

gene

Answer 2

sequence of DNA that codes for a trait

Question 3

allele

Answer 3

variation of a gene

found at the same loci on both chromosomes in a homologous pair

Question 4

wild type allele

Answer 4

normal allele most common in nature

Question 5

mutation

Answer 5

HERITABLE change in DNA

Question 6

hemizygous

Answer 6

only one allele is present

example- men only have one X and one Y chromosome which contain hemizygous genes

Question 7

penetrance

Answer 7

proportion of individuals who have the phenotype associated with a specific allele

complete penetrance- the gene for a trait is expressed in all the population who have the gene

incomplete penetrance- the genetic trait is expressed in only part of the population

Question 8

expressivity

Answer 8

the degree of a certain phenotype for a given genotype

every kid has curly hair, but the curls look different

Question 9

incomplete dominance

Answer 9

heterozygous will have intemediate state

ex. red and white make pink

Question 10

example of multiple alleles

Answer 10

there are more than two allele options- ex, blood typing

Question 11

epistasis

Answer 11

one gene affects the expression of a different gene

ex baldness covers the gene for the colour of hair

Question 12

pleitoropy

Answer 12

one gene is responsible for many traits

ex. cystic fibrosis gene rewsponsible for many symptoms

Question 13

polygenic inheritance

Answer 13

many genes responsible for one trait

gives the trait continous variation

Question 14

haploinsufficiency

Answer 14

one copy of the gene is lost and the expression of the remaining copy is not sufficient enough to have normal phenotype

results in intermediate phenotype

Question 15

proto oncogenes

Answer 15

can become oncogenes due to GAIN OF FUNCTION mutations

follow one hit hypothesis

Question 16

gain of function mutations

Answer 16

cause too much protein to be made or production of an over active protein leading to cancerous growth

Question 17

one hit hypothesis

Answer 17

gain of function mutation in one copy of the gene turns it into an oncogene

Question 18

tumor supressor genes

Answer 18

become cancerous due to loss of function mutations

two hit hypothesis

haplosufficient !!

Question 19

two hit hypothesis

Answer 19

loss of function mutation is needed in both copies of the gene to make it cancerous

Question 20

null alleles

Answer 20

come from mutations that lead to a lack of normal function in alleles - tumor supressor genes have null alleles when they become cancer causing

Question 21

p53

Answer 21

tumor supressor gene that is known as the guardian of the cell

upregulated to prevent cells from becoming cancerous

Question 22

p21

Answer 22

another tumor supressor gene that inhibits phosphorylation activity to decrease rampant cell division

Question 23

retinoblastoma gene

Answer 23

tumor supressor gene that codes for retinoblastoma protein

prevents excessive cell growth during interphase

Question 24

what are the three laws of gregor mendel

Answer 24

law of dominance
law of segregation
law of independent assortment

Question 25

law of segregation

Answer 25

homologous gene copies separate during meiosis anaphase I

Aa individual produces gametes with A and a alleles

Question 26

law of independent assortment

Answer 26

Homologous chromosomes line up independently during metaphase I of meiosis so that alleles separate randomly (this increases genetic variability).

The law of independent assortment can produce 2^23 options (23 homologous chromosome pairs split).

Question 27

non disjunction

Answer 27

improper segragatino of chromosome pairs during anaphase

single nondisjunction of chromosomes during meiosis i

single nondisjunction of chromosomes during meiosis II

single nondisjunction of chromosomes during mitosis

Question 28

single nondisjunction of chromosomes during meiosis i

Answer 28

24, 24, 22, 22

Question 29

single nondisjunction of chromosomes during meiosis II

Answer 29

24, 22, 23, 23

Question 30

single non disjunction in mitosis

Answer 30

47, 45

Question 31

aneuploidy

Answer 31

abnormal number of chromosomes in the daughter cell which leads to trisomy or monosomy after fertilization

disomy- normal diploid cell

Question 32

down syndrome

Answer 32

trisomy of the 21st chromosome

each diploid cell have 47 chromosomes total

Question 33

turner syndrome

Answer 33

monosomy of the X chromosome in females

each diploid cell has 45 chromosomes

physical abnormalities and sterility

Question 34

klinefelters syndrome

Answer 34

trisomy of the sex chromosomes in males giving XXY and 47 chromosomes

intelectual issues
physical issues
and reproductive issues

Question 35

trisomy x

Answer 35

trisomy of x chromosomes in females

learning disabilities and attention issues

Question 36

test cross

Answer 36

pairs an individual of unkown genotype with one that is homozygous recessive

Question 37

where can mendels three laws be studied

Answer 37

in the f2 generation

Question 38

dihybrid cross

Answer 38

examines the inheritance of two genes on separate chromosomes

Question 39

females and males on pedigree charts

Answer 39

females- cicles
males- square

Question 40

recombinant vs non recombinant gametes

Answer 40

recombinant- receive gentically unique chromatids

nonrecombinant- receive parental chromatids- did not undergo crossing over

Question 41

linked genes

Answer 41

found close tog on the same chromosome

deduce relative distance between genes by looking at recombination frequencies

Question 42

map unit

Answer 42

1% of recombination bw two genes (1cM- centrogram)

Question 43

recombination frequency of _ means genes are linked

Answer 43

less than 50% means they are linked

Question 44

when genes are perfectly linked, they have a recombination frequency of

Answer 44

0

Question 45

linkage maps

Answer 45

tables used to determine the probability of inheritance

use map units to infer distance between genes on a chromosome

Question 46

haplotype

Answer 46

group of genes usually inherited tog bc they are close to each other on the chromosome

Question 47

epigenetics and twins

Answer 47

cause monoxygous twins to have different susceptibilities to the same disease

Question 48

genomic imprinting

Answer 48

genes expressed depending on parental origin - influenced by epigenetic factors

only one copy of gene in individual expressed- either from mom or dad and the other is expressed

diff from sex linked triats bc they come from autosomal chromosomes (non sex chromosomes)

Question 49

histone methylation vs DNA methylation

Answer 49

histone methylation- either upregulate or downregulate

DNA methylation- supresses gene expression - prevent transcription factors from binding

Question 50

x linked dominiant

Answer 50

Dominant inheritance on the
X chromosome. Any offspring (male or female) that receive the affected allele will end up with the disorder.

Question 51

x linked recessive

Answer 51

Recessive inheritance on the X chromosome. For males, only one affected allele is needed to cause the disorder. For females, two affected alleles are needed to cause the disorder because females have two X chromosomes. Hemophilia and color-blindness are examples of X-linked recessive conditions.

Question 52

y linked

Answer 52

Inheritance on the Y chromosome. Can
only be passed from father to son. Will always be expressed whether it is dominant or recessive because males only have one Y chromosome.

Question 53

x inactivation

Answer 53

process by which one of females x chromosomes is inactivated forming a Barr body and preventing excess transcription

female carrier can become affected for a disease if her unaffected x vhromosome with wild type allele is inactivated