Week 4

Question 1

dna cloning

Answer 1

allows isolation of dna segment and replicate it independently of original context

can make large quantities, can manipulate, etc

Question 2

restriction enzymes

Answer 2

recognize and cut dna at specific sequences

cells defense against invading dna
-EcoRI, etc.

recognition sequences of different lengths

Question 3

ligase

Answer 3

covalently attaches dna segments to each other

Question 4

vector

Answer 4

dna that has origin of relocation and can accept foreign dna segments

Question 5

life cycle of virus

Answer 5

virus enters cell, gets replicated, transcribed, then viral particles released from cell

RNA virus—made into dna, can be integrated into host genome, code proteins made (reverse transcriptase)

Question 6

bacteriophages

Answer 6

viruses that infect bacteria

certain bacteria cannot be infected by these—host restricted

Question 7

palindromic

Answer 7

same meaning forward or backward

restriction enzymes often palindromic

Question 8

plasmids

Answer 8

circular dna molecules in bacteria

origin allowing dna replication

often carry resistance genes against antibiotics

Question 9

joining of two different dna fragments

Answer 9

join complementary staggered ends, used ligase (if from same restriction enzyme)

Question 10

recombinant dna: prereqs

Answer 10

bacteria produce restriction enzymes that recognize specific DNA sequences

bacteria can contain plasmids

Bacteria can take up foreign dna

Ligase to put together

Question 11

reverse transcriptase

Answer 11

enzyme isolated from retroviruses

reads mRNA into dna, etc.

Question 12

Gregor Mendel

Answer 12

priest in Austria, bred pea plants

realized that there is genetic material—ahead of his time, ignored

Question 13

crossing of peas

Answer 13

yellow seeded peas and green seeded

F1 generation 100% yellow

then self fertilization, 75% yellow

• comes from eggs and sperm having gametes
• green peas recessive (lower case)

Question 14

Mendel’s first law

Answer 14

law of segregation: each individual receives 2 factors (alleles), one from each parent, and each gives one of these two factors to gametes (germ cells) and thus to next generation

Question 15

homozygous

Answer 15

if factors are identical (for a trait/gene)

if not, hetero

Question 16

genotype

Answer 16

genetic constitution of an individual

Question 17

phenotype

Answer 17

appearance or attributes of an individual

Question 18

locus

Answer 18

place in the genome that is defined—can be a trait, a specific gene, or a specific nucleotide

position in a chromosome of gene or chromosome marker

• names in human genome assigned by committee, italicized in publications
• can be a specific gene, or a specific base

Question 19

allele

Answer 19

one of several possible forms of a locus

eg y and Y in the pea case—recessive and dominant alleles

Question 20

law of independent assortment

Answer 20

Genetic factors are distributed independently

Question 21

closely linked loci

Answer 21

two loci in same chromosome, same phenotype…

Question 22

Mendelian

Answer 22

a trait of disease that follows the laws of Mendel

Question 23

recessive disease (human)

Answer 23

called if the wild type is dominant—i.e. if 2 defective copies are needed to get disease

Question 24

dominant disease

Answer 24

if inherited through generations, one disease allele is sufficient to cause the disease

Question 25

additive traits

Answer 25

not all traits are dominant or recessive

examples: height, blood pressure, skin color, risk for depression, diabetes, obesity

Question 26

genetic marker locus

Answer 26

dna segment with an identifiable physical location on a chromosome and inheritance can be tracked

usually used an indirect way of tracking inheritance pattern if gene that has not yet been identified

Question 27

mutation

Answer 27

change in some disciplines, disease causing change in others

Question 28

polymorphism

Answer 28

meaning non-disease-causing change, or change found at a frequency of 1 percent or higher in the population

coming in many different forms

Question 29

sequence variant

Answer 29

different than what’s in standard database, avoids confusion with mutation vs polymorphism

Question 30

micro satellite markers

Answer 30

genetic marker: alleles that show high degree of variation and are known to be on specific region of chromosome

length variants of short, simple sequence (also called STRP—short tandem repeat polymorphisms)

can be 4-10 alleles of different length at marker locus

13 of this is enough to identify human

pcr amplifies with flanking primers

Question 31

single nucleotide polymorphism (snp)

Answer 31

any single base change

Most common in mammals: cpg to tpg

several million snps are already publicly available, there are hundreds of snps for each gene

verified

in locus region (win 2kb of gene including introns)

heterozygosity: fraction of human subjects that are heterozygous

Question 32

lof mutation/snps

Answer 32

loss of function: nonsense(stop) or splice

Question 33

coding snps

Answer 33

in the coding part of the mRNA

• synonymous (does not change the amino acid sequence)
• nonsynonymous

Question 34

linkage

Answer 34

caused by loci being close to each other on a chromosome

genes and genetic markers can be separated by a recombination factor—the prob that in any meiosis, there will be a recombination between them

theta = 0.5 indicated complete lack of linkage, theta = 0 indicates very tight linkage

Question 35

lod score

Answer 35

probability of this particular family constellation if the marker and diseas elocus are linked, and 10 percent recombination between them

lod score if 3 traditionally the threshold to declare linkage