Genetics

Question 1

Karyotype

Answer 1

picture of an individuals 23 pairs of chromosomes

Question 2

How many autoosomal chromosomes pairs do we have?

Answer 2

22

Question 3

acro-centric chromosome

Answer 3

centromere is closer to the head of the chromosome than the bottom, chromosomes 13, 14, 15, 21, and 22

Question 4

2 alleles for eye color

Answer 4

dominant (brown)/recessive (blue)

Question 5

what is the area of crossing over between homologous chromosomes called?

Answer 5

chiasma

Question 6

In which phase of meiosis does crossing over occur?

Answer 6

prophase I

Question 7

disjuction

Answer 7

when sister chromatids separate during Meiosis II

Question 8

when do alleles for a single gene separate?

Answer 8

anaphase I (mendel’s 1st law)

Question 9

what is mendel’s 2nd law?

Answer 9

independent assortment - gametes get one maternal or paternal chromosome (though he did not understand linkage- so law is true unless alleles are linked)

Question 10

incomplete dominanace

Answer 10

heterozygous exhibit intermediate phenotype

Question 11

penetrance

Answer 11

proportion of individuals in a population with a genotype, who actually express the phenotype

Question 12

expressitivity

Answer 12

the degree to which an individual expresses a given genotype as a phenotype

Question 13

mutagens

Answer 13

things that cause mutations - chemicals (free radicals, carcinogens), ionizing radiation (xrays, UV light), spontaneous mutation

Question 14

point mutation

Answer 14

one nucleotide is swapped for another

silent - no amino acid change, no affect on protein (usually the 3rd base - wobble, in intron or junk DNA)

missense - 2nd base is swapped, changes one amino acid (if amino acids are similar, may not affect protein)

nonsense - creation of a stop codon, severely alters protein

Question 15

frameshift mutatin

Answer 15

insert or delete a nucleotide

changes from entire reading frame from mutation foreward - every AA after that is different from original

severely affects protein

Question 16

chromosomal mutations

Answer 16

large parts of the chromosome are affected - can get rid of, duplicate, or invert sections of the chromosome.

some involve multiple chromosomes

insertion - DNA is moved from one chrom to another

Question 17

translocation

Answer 17

DNA from one chromosome is swapped with DNA from another

Question 18

nondisjunction

Answer 18

chromosomes fail to separate

ex: turner syndrome monosomy X, klinefelter syndrome trisomy XXY, down syndrome trisomy 21

Question 19

How can yo tell if a trait is dominant?

Answer 19

parents exhibit trait, any # of children do not

Question 20

how can you tell if a trait is X-linked recessive?

Answer 20

affects only or mostly males, parents may not show the trait but offspring do

Question 21

codominance

Answer 21

multiple traits are expressed

Question 22

Incomplete dominance

Answer 22

the trait is a combination from the two alleles

Question 23

point mutation

Answer 23

replaces a single nucleotide with a different nucleotide

Question 24

missense mutation

Answer 24

changes a codon to encode a different amino acid

Question 25

nonsense mutation

Answer 25

changes a codon to a stop condon

Question 26

frameshift mutation

Answer 26

inserts or deletes a nucleotide; shifts the sequence, affecting all subsequent codons

Question 27

In a familial genetic tree, what type of trait is indicated by two unaffected parents having two affected children?

Answer 27

autosomal recessive - parents are both carriers, but neither of their children are affected

Question 28

In a familial genetic tree, what type of trait is indicated by two affected parents having two unaffected children?

Answer 28

autosomal dominant - both parents are heterozygotes, yet they express the trait/disease

Question 29

How does gene regulation work in prokaryotes?

Answer 29

Either inducible system or repressible system.

inducible: repressor is bound to the operator site unless an inducer inhibits it and RNA polymerase is allowed to transcribe the genes. (positive feedback)
repressible: regulator is non-functional unless a corepressor binds with it to stop transcription (negative feedback)