Unit 4 genes/genomes part

Question 1

Micro and minisatellites can be used for what? How?

Answer 1

Used for genetic mapping.

If parent 1 has 2 alleles (6 VNTR, 9 VNTR) and parent 2 has 2 alleles (5 VNTR, 7 VNTR) alleles will differ by number of repeats at a mini-satellite locus, so digestion generates restriction fragments that differ in length

progeny will receive 1 allele from each parent. AKA shows that 50% of the bands in an individual are inherited from a particular parent

Question 2

What is a variable number tandem repeat (VNTR)

Answer 2

very short repeated sequences that include microsatellites and minisaellites

-used in forensic science

Question 3

When mRNA is expressed at low levels…

Answer 3

mrna will overlap of extensively when different cell types are compared

Question 4

What is a housekeeping gene? what can it be used for?

Answer 4

a gene that is theoretically expressed in all cells b/c it provides basic functions needed for maintenance of all cell types.

-can be used to determine if a gene is over-expressed

Question 5

Whaat is a luxury gene ?

Answer 5

a gene encoding a specialized function usually synthesized in large amounts in a particular cell.

Question 6

What is a satellite DNA?

Answer 6

short sequences repeated several times aka

DNA that consists of many tandem repeats (identical or related) of short basic repeating units

-satellites are not translated and can be polymorphic. They are also found in the heterochromatic region or centromeres possibly has a structural role in chromosome segregation

Question 7

What is a minisatellite DNA?

Answer 7

DNA that consists of repeated copies of short repeating sequence w/more repeat copies than microsatellite but fewer than satellite DNA

length of repeating units is measured in tens of base pairs

Question 8

Abundant mRNA

Answer 8

Consists of small number of individual species , each present in large numbers of copies per cell

Question 9

Scarce mRNA?

Answer 9

mRNA that consists of a large number of individual mRNA sequences, each present in very few copies per cell

Question 10

How can the proportion of protein coding DNA be measured?

Answer 10

by measuring DNA that hybridizes to mRNA isolated from cell

Question 11

All all genes essential genes?

Answer 11

NO, only in protein synthesis are 50% of genes essential

Question 12

What is meant by redundant gene ?

Answer 12

Usually 2 or more genes are redundant when mutation in any one of these genes does not produce a detectable disease - in a way redundancy protects cells from gaining mutations

Question 13

What are the three regions on the Y chromosome? what is their role?

Answer 13

1) X transposed region - regions is transposed from x chromosome
2) X degenerate region - sequence w/common origin w/X chromosome
3) Amplicons - sequences repeated on Y chromosome

Question 14

How does Y chromosome differ from X?

Answer 14

60% of Y chromosome is expressed in testes.

Y chromosome is smaller and has less genes than X. It is also haploid b/c there is only 1 copy of chromosome

Question 15

TRUE OR FALSE: In prokaryotes, the number of genes is proportional to genome size and in eukaryotes the number of genes does not correlate w/genome size or complexity

Answer 15

TRUEEE

Question 16

In yeast, what are the origin of replication?

Answer 16

The ARS (autonomous replicating sequences), which are short A-T sequences w/11 base pair sequence that is called the A domain

Question 17

What is the ORC in yeast?

Answer 17

origin recognition complex that is made up of 6 proteins and binds to the ARS in yeast

Question 18

What is the licensing factor?

Answer 18

proteins that are necessary for replication. Each replicon can only be initiated once!

Question 19

Prior to replication the nucleus contains an active licensing factor, what happens after replication?

Answer 19

the Licensing factor in the nucleus is inactive and licensing factor in the cytoplasm cannot enter the nucleus.

-dissolution of nuclear membrane during mitosis will allow LF to associate w/nuclear material aka enter the nucleus. after cell division generates daughter cells with LF in nucleus

Question 20

What are the two licensing factors that bind to the ORC?

Answer 20

cdc6 and cdt1

Question 21

What is MCM?

Answer 21

replication helicase in orc yeast

Question 22

How are okazaki fragments made in mammals?

Answer 22

1) okazaki fragment displaces RNA primer
2) flapp is formed
3) FEN1 cleaves flap
4) adjacent fragments are ligated by ligase AMP

Question 23

what is a linkage map?

Answer 23

a linkage map shows the percent of recombination between two genes and is measured in lmu. linkage maps do not represent physical distance.

equation: #of recombinant offspring/total # offspring x 100% = lmu

Question 24

What are restriction maps? How are they made?

Answer 24

represents physical distance between genetic markers

1) cut DNA fragments
2) measure length of each fragment

**restriction map is independent of gene function, thus if there is no phenotypic variation, we can still detect RFLPs using restriction maps

Question 25

What is meant by polymorphism? How are these shown on restriction maps?

Answer 25

variation! When there are multiple alleles at a specific location. alleles can have different mutations that may alter phenotype.

Restriction maps of such alleles would also be polymorphic provided that mutations were at a restriction enzyme target site. Each map/sequence would be different from each other.

***if changes do not affect function then we don’t observe polymorphism at phenotypic level

Question 26

What are RFLPs?

Answer 26

Restriction fragment length polymorphism (RFLP) results from variation in the DNA sequence recognized by restriction enzymes (point mutation on restriction enzyme). These are bacterial enzymes cut DNA molecules at known locations. They are independent of gene function so we can still identify RFLPs

Question 27

what does it mean if a restriction map is associated w/a phenotypic trait?

Answer 27

That the restriction site is close to the gene for that specific phenotype.

EX: comparing restriction maps of healthy individual vs single gene disorder individual - you will find a particular restriction site always present or absent in patients. We could say that the restriction marker is closely linked to the disease gene.

Question 28

What are SNPs?

Answer 28

single nucleotide polymorphism.

SNPs cause a change in one single nucleotide and are responsible for most genetic variations seen w/in populations

Question 29

TRUE OR FALSE: RFLPs are SNPS

Answer 29

true, they are SNPs located in the restriction enzyme recognition site.

Question 30

What can SNP and RFLP maps be used for?

Answer 30

used for establishing parent /offspring relationship.

Question 31

What is a haplotype?

Answer 31

DNA variations or polymorphisms that are inherited together. So it can be the combination of alleles in a region or a set of SNPs on the same chromosome

Question 32

Following denaturing of a genome, what does measuring kintetics (or renaturing) the same genome allow?

Answer 32

to identify sequences based on the frequencies of repetitions in genomes

Question 33

Kinetics of DNA reassociation show what two type of frequencies?

Answer 33

1) Non repetitive DNA, appear only once -polypeptides are encoded by non-repetitive DNA
2) Repetitive DNA, which is present more frequently and can be divided into moderately repetitive or highly repetitive.

Question 34

TRUE OR FALSE: Large genomes contain more genes than small genomes?

Answer 34

FALSE: large genomes do NOT contain more genes, rather they contain large amount of repetitive DNA

Question 35

What is the difference seen repetitive/nonrepetitive DNA in bacteria vs amphibias/plants ?

Answer 35

Bacteria - 100% nonrepetitive

Amphibians/plants: 80% moderately and highly repetitive

Question 36

What occurs to the genes as complexity of organism increase?

Answer 36

the number of minimum genes also increases