Genetics week 1

Question 1

Gene

Answer 1

segment of DNA that encodes a specific thing (amino acid, regulational RNA etc.)

Question 2

Allele

Answer 2

alternative forms of a gene (DNA at a specific locus) that differ in sequence

Question 3

Locus

Answer 3

a physical region of a chromosome; often used to refer to segment of DNA that contains a specific gene

Question 4

Genetics

Answer 4

science of genes/DNA

Question 5

Homologous chromosomes

Answer 5

chromosomes that pair during meiosis one derived from each parent. Although not identical, normally only a few base pair differences in each gene

Question 6

sister chromatids

Answer 6

2 identical duplicated chromosomes joined by a single centromere

Question 7

Ploidy

Answer 7

the number of copies of the c-some

Question 8

Haploid

Answer 8

one copy of each c-some

Question 9

Diploid

Answer 9

2 copies of each c-somes

Question 10

Aneuploid

Answer 10

any number of c-some that is not an exact multiple of the haploid number

Question 11

Monosomy/Trisomy

Answer 11

result of nondisjunction during meiosis or mitosis resulting in the absence of a single c-some or the presence of an extra c-some

Question 12

Maternal serum ARP screening/Quad test

Answer 12

this is a screening test, it does not diagnose a problem; it only signals that further testing should be done

Measures serum alpha-fetoprotein

Question 13

somatic cell

Answer 13

other than those of the gamete-forming germ line

Most somatic cells in humans are diploid

Question 14

germ line cells

Answer 14

cells responsible for the production of gametes

Question 15

gametes

Answer 15

haploid germ cells (sperm and ova)

Question 16

zygotes

Answer 16

two gametes fuse (fertilization)

Question 17

Mitosis

Meiosis

Answer 17

Mitosis is the general propagation of cells, end up with diploid cells

Meiosis utilizes another propagation of division, end up with haploid cells

Question 18

crossing over

Answer 18

exchange of genetic material between homologous c-somes that results in recombinant c-some

Question 19

synapsis

Answer 19

binding of the 2 homologous c-somes

Question 20

spermatogenesis

Answer 20

mitosis occurs throughout life. At puberty meiotic division is induced with millions of sperm being produced

Continues throughout life

Question 21

Oogenesis

Answer 21

all mitosis occurs in development

At birth, all precursor cells arrested in prophase division 1. At puberty, 1 oocyte matures (finished meiosis) and is released per cycle

Ends at menopause

Question 22

Advanced paternal age is associated with what kind of mutation?

Answer 22

replication errors, single BP mutation

Question 23

Advanced maternal age is associated with what of mutation?

Answer 23

trisomies and non disjunction

Question 24

Promoter sequences

Answer 24

controls levels of mRNA expression which controls levels of protein expressed

Question 25

coding sequences

Answer 25

exons, specify the sequence of amino acids in proteins

Question 26

Intervening sequences

Answer 26

introns, interrupt coding sequences. mRNA splicing

Question 27

Structural regions

Answer 27

Untranscribed regions and 5’-3’ untranslated regions in mRNA

Question 28

core basal promoter

Answer 28

determines the transcription star site, and whether transcription occurs

ex. TATA box

Question 29

Regulatory Domains (elements)

Answer 29

They determine when where and how much transcription occurs

ex. enhancers

Question 30

Conservative missense mutation

Answer 30

Point mutation that alters one amino acid to another amino acid with similar properties

ex. Ile -> Leu

Question 31

Non-conservative missense mutation

Answer 31

Point mutation that alters one amino acid to another amino acid w/ different properties

ex. Ser -> Phe

Question 32

Nonsense mutation

Answer 32

point mutation that results in premature stop codon

results in truncated protein

Question 33

Promotor mutations

Answer 33

effect levels of protein expression by effecting levels of RNA expression

Question 34

Haplosufficiency

Answer 34

one normal allele is enough to mask the effects of the mutant

recessive disorder

Question 35

Haploinsufficiency

Answer 35

one normal allele is NOT enough to mask the effects of the mutant allele (dosage sensitivity)

Dominant disorders

Question 36

Gain of Function mutation

Answer 36

novel protein product or over-expression/mis-expression (ex. in wrong tissue) of a normal protein

ex.dominant disorders like Trisomies

Question 37

Dominant negative mutation

Answer 37

mutant protein inhibits the activity of the normal protein

ex. multimeric proteins

Question 38

Principle of Segregation

Answer 38

genes occur in pairs in individuals, one copy inherited from each parent; only one of each is transmitted to the offspring in the next generation

Question 39

Principle of Independent Assortment

Answer 39

alleles of different genes are transmitted independently

Not true for genes that are located close together (linkage)

Question 40

genotype

Answer 40

the genetic constitution of an individual, or the two alleles inherited at a specific genetic locus

Question 41

phenotype

Answer 41

observable consequence of a given genotype and environment

Question 42

co-dominant

Answer 42

the phenotype of the heterozygote is distinguishable from either of the homozygotes

Question 43

Risk of occurence

Answer 43

probability that a couple will have an affected child.

Depends on population frequencies of the disorder and the rate of spontaneous mutation

Question 44

Risk of recurrence

Answer 44

the probability that a genetic disorder that has occurred in a family will recur in another member in the same or in future generations.
Depends on mode of inheritance

Question 45

gene frequency

Answer 45

percentage of a specific allele of a gene in a population

Question 46

genotype frequency

Answer 46

proportion of a population w/ a specific genotype (combo of 2 alleles)