Genetics

Question 1

Transcription

Answer 1

mRNA synthesis

in nucleus

Question 2

How is mRNA different from DNA?

Answer 2

single stranded
ribose backbone, not deoxyribose
Us instead of Ts

Question 3

Translation

Answer 3

protein synthesis

in ribosome

Question 4

codon

Answer 4

on mRNA

3 base pairs: code for amino acid

Question 5

ribosomes

Answer 5

protein factory
make protein out of codon from mRNA and anticodon on tRNA
either in cytoplasm or rER

Question 6

How many nucleotides? amino acids? codons?

Answer 6

4 possible nucleotides, each w/ 3 base pairs: 4^3=64 possible codons to code for 20 amino acids
allows for redundancy in translate table

Question 7

single nucleotide polymorphism (SNP)

Answer 7

base pair subsitution
at most only 1 amino acid is changed
very common
allow for no 2 people to look the same

Question 8

Frame shift mutation w/ one base pair inserted or deleted

Answer 8

the rest of the strand will be messed up
protein won’t work
results will be devastating, t/f uncommon

Question 9

Single gene disorders

Answer 9

Dominant
Recessive
X-linked: recessive or dominant

Question 10

Dominant single gene disorder

Answer 10

2 copies of each gene (1 from each parent)
If one bad gene, half of the protein will be bad
If the half bad protein causes a problem, its a dominant disorder

Question 11

Recessive single gene disorder

Answer 11

need 100% problem to cause disease
both genes must be defective
If only 1 gene is bad, it will be overcome by the good proteins

Question 12

X-linked single gene disorder

Answer 12

Recessive: all of the Xs need to be defective (from both parents)
More of a problem for males

Question 13

Translocations

Answer 13

genetic material from 1 chromosome mistakenly put on another chromosome

Question 14

Deletions

Answer 14

genetic material deleted from a chromosome

Question 15

Nondisjunction

Answer 15

abnormal # of chromosomes (aneuploidy)
leads to trisomy or monosomy
incorrect separation of chromosome in Meiosis I or Meiosis II
can occur on any chromosome, but only 21, 18, 13 or X are survivable
usually Trisomy
normal: 44 chromosomes + XX or XY

Question 16

Down syndrome

Answer 16

Down: trisomy 21
maternal age increases chance of trisomy
intellectual disability, facial abnormalities, cardiac problems

Question 17

Turner syndrome

Answer 17

(45:X)
44 chromosomes + X
only monosomy that survives to term and is consistent with life
infertile females
cardio problems

Question 18

Klinefelter syndrome

Answer 18

47:XXY
infertile males (some are fertile)
slight decrease in IQ

Question 19

polyploidy

Answer 19

chromosome sets that don’t = 2
partial mole: triploid: 2X from dad & 1X from mom
usually 69:XXX or 69:XXY
ocassionally go to term but don’t live long

Question 20

locus

Answer 20

location in the genome

Question 21

allele

Answer 21

one member of a pair of genes (1 allele from mom, 1 from dad)

Question 22

Genotype

Answer 22

genetic material

Question 23

Phenotype

Answer 23

physical manifestation

Question 24

Penetrance

Answer 24

the chance that phenotype follows genotype

Question 25

Haplotype

Answer 25

alleles on a single chromosome

Question 26

Recombination/crossover

Answer 26

gene rearrangement btw homologous chromosomes occurs during prophase I of meiosis allows for new arrangement of maternal and paternal alleles on same somatic chromosome

Question 27

Structure of chromosomes

Answer 27

2 chromatids attached at the middle by centromere 2 short arms and 2 long arms P: petite arm Q: long arm

Question 28

SNP

Answer 28

single nucleotide polymorphism

Question 29

somatic cell

Answer 29

body cells; not sex cells reproduced by mitosis 46 (2 pairs of 23) chromosomes in each cell: 22 autosomal and 1 pair sex chromosomes diploid cell

Question 30

gamete

Answer 30

sex cells: egg or sperm only 1 copy of each chromosome haploid cell

Question 31

karyotype

Answer 31

chart that places homologous chromosomes in size order matching shape and banding patterns

Question 32

euploid cells

Answer 32

balanced set of chromosomes (in relation to haploid #

Question 33

aneuploid cell

Answer 33

abnormal # of chromosomes (in relation to haploid #)

Question 34

meiosis

Answer 34

how a diploid cell divides for sexual reproduction into 4 haploids 2 fissions occur of the nucleus 4 gametes created: each have 1/2 the # chromosomes as original cell mixing of chromosomes occur

Question 35

What happens if nondisjunction occurs during meiosis I?

Answer 35

all gametes are affected 2 have 1 extra chromosome 2 have 1 less chromosomes

Question 36

What happens if nondisjunction occurs during meiosis II?

Answer 36

half of the gametes are affected 2 normal 1 has 1 extra chromosome 1 has 1 less chromosome

Question 37

At the end of meiosis, how many of the 4 haploids become sex cells in males? Females?

Answer 37

males: keep all 4: 4 sperm cells females: 1 ova, and 3 polar bodies

Question 38

When does meiosis occur in females? | Males?

Answer 38

Females: all in fetal ovary males: after puberty

Question 39

What does crossover allow for?

Answer 39

genetic diversity

Question 40

What are some errors of crossover?

Answer 40

uneven crossover: 2 copies of a gene deletion of a gene: cri du chat * we tolerate additional DNA better then missing DNA

Question 41

What is chromosome translocation?

Answer 41

cross over btw non-homologous chromosomes (i.e. chromosome 1 from mom and chromosome 2 from dad mix together)

Question 42

If a child has balanced translocation how will this affect them?

Answer 42

They will have the right amount of DNA but when they go to have kids, the chances of combining DNA in the correct amounts is very low: alot of spontaneous abortions Also...problems at the edges w/ mutated proteins: increased risk of Ca

Question 43

What are some examples of Dominant single gene disorders?

Answer 43

``` Familial hypercholesterolemia Huntington Achondroplasia Marfan Retinoblastoma Li-Fraumeni ```

Question 44

What are some examples of Recessive single gene disorders?

Answer 44

``` sickle cell anemia cystic fibrosis lysosomal storage diseases (Tay-Sachs, Gaucher, Nieman-Pick) Phenylketouria Glycogen storage disease ```

Question 45

What are some examples of X-linked recessive single gene disorders?

Answer 45

``` Duchenne muscular dystrophy Hemophilia A (factor VIII) or B (IX) ```

Question 46

``` In a pedigree, what does each symbol mean? empty circle empty square empty diamond darkened square or circle square or circle w/ line through it ```

Answer 46

empty circle: unaffected female empty square: unaffected male empty diamond: unknown sex darkened square or circle: affected male or female square or circle w/ line through it: dead

Question 47

If 2 people have a dominant disease (Dd), how likely is it that they will have a: homozygous affected heterozygous affected homozygous normal

Answer 47

homozygous affected: 25% (rare) heterozygous affected: 50% homozygous normal: 25%

Question 48

If 1 person has a dominant single gene disorder (Dd) mates with a normal person (dd), how likely is it that they will have a: homozygous affected heterozygous affected homozygous normal

Answer 48

homozygous affected: 0 heterozygous affected: 50% homozygous normal: 50%

Question 49

If 2 people are carriers of a recessive single gene disorder, what is the likelyhood they will have a homozygous affected heterozygous carrier homozygous normal

Answer 49

homozygous affected: 25% heterozygous carrier: 50% homozygous normal: 25%

Question 50

How does X inactivation work?

Answer 50

occurs in embroyo of female: inactivation occurs and cells will either have an active paternal X or maternal X "X chromosome mosaics"

Question 51

If a normal male mates w/ a female carrier of an X-linked recessive gene, what is the likelyhood that there will be a normal daughter/ son carrier daughter/son affected daughter/son

Answer 51

normal daughter: 25%; son: 25% carrier daughter: 25%; males: 0 affected son: 25%; females: 0

Question 52

If a normal female mates w a male affected by an X-linked recessive disease, what is the likely hood they will have a normal daughter/ son carrier daughter/son affected daughter/son

Answer 52

normal daughter: 0 son: 50% carrier daughter: 50% son: 0 affected daughter/son: 0

Question 53

if a carrier female mates w/ a male w/ a recessive gene disease, what is the likely hood they will have: normal daughter/ son carrier daughter/son affected daughter/son

Answer 53

normal daughter: 0 son: 25% carrier daughter: 25% son: 0 affected daughter: 25% : 25%

Question 54

What are epigenetic modifcations?

Answer 54

we can actually turn off some genes - generation skipping phenomena - genes that are methylated can't be expressed but can be passed to your offspring