L3

Question 1

what is spacer DNA

Answer 1

unique non coding DNA

Question 2

what are non coding functional sequences

Answer 2

do not produce proteins but still important

Question 3

what are human globin genes for

Answer 3

codes for oxygen carrying molecule in humans

Question 4

what is a heme

Answer 4

iron carrying molecule

Question 5

true or false, eukaryotic genomes tend to be larger than prokaryotes

Answer 5

true

Question 6

true or false, there is no relationship between genome size and phenotypic complexity

Answer 6

true

Question 7

true or false, the number of genes in a species is often lower than expected when compared to the size of its genome

Answer 7

true

Question 8

true or false, there is no strong relationship between genome size and number of genes

Answer 8

true

Question 9

which has fewer genes but a larger genome in a given number of base pairs, eukaryote or prokaryote

Answer 9

eukaryote

Question 10

true or false, of the genomes sequenced so far, humans and other mammals have the lowest gene density

Answer 10

true

Question 11

what do the genes of most bacteria consist of

Answer 11

genes for proteins tRNA or rRNA with the remaining consisting of non transcribed regulatory regions

Question 12

true or false, in eukaryotes the vast majority of DNA neither encodes protein nor is transcribed into RNA of known function

Answer 12

true

Question 13

true or false, humans have 10 000 times as much non coding DNA as bacteria

Answer 13

true

Question 14

what are unique sequence DNA

Answer 14

aka spacer DNA
mainly consist of genes which in addition to coding regions contain intervening sequences that are not translated ( has exons and introns).

Question 15

true or false, gene related regulatory sequences and introns account for 20% and 5% of the human genome respectively, the remainder is 15% unique non coding DNA

Answer 15

true

Question 16

what are pseudogenes

Answer 16

non functional gene within a family of genes

Question 17

why have some genes evolved into tandem arrays

Answer 17

this is because cells need a large amount of products of those genes

Question 18

what is the purpose of telomeres

Answer 18

it acts as a cap stabilizing the end of the chromosome and stops it from being degraded; the G rich strand often protrudes beyond the complementary C-rich strand at the end of the chromosome

Question 19

true or false, special proteins bind to the single-strand sequence protecting the telomere from degredation

Answer 19

true

Question 20

what does the telomeric sequence solve

Answer 20

solves the problem of replicating the ends of a linear DNA molecule

Question 21

what enzyme can extend the G-overhang

Answer 21

telomerase (reverse transcriptase)

Question 22

where is telomerase present

Answer 22

in single-celled organisms, germ cells, early in embryonic cells and certain somatic cells

Question 23

true or false, most somatic cells have little or no telomeras activity

Answer 23

true

Question 24

true or false, once the telomeres have shortened beyond a critical point the chromosome becomes unstable

Answer 24

true

Question 25

what are centromeric repeats

Answer 25

highly repeat sequences with no known function

Question 26

what are centromeric repeats also known as and what type of chromatin are they usually

Answer 26

aka satellite DNA, usually heterochromatic, short A-T rich tandem repeats flanking the centromeres

Question 27

what are variable number of tandem repeats (VNTRs)

Answer 27

A DNA sequence consistent of variable number of tandem repeat units

Question 28

what are the two principal families of VNTRs

Answer 28

microsatellites and minisatellites

Question 29

what is a microsatellite

Answer 29

The repeat unit in microsatellite is 2-6 bp long | most common is repeat CA complement GT

Question 30

what is a minisatellite

Answer 30

between 15-100 bp long

Question 31

what uses do mini and micro satellites have

Answer 31

can be used in DNA fingerprinting and paternity tests

Question 32

What are transposable elements

Answer 32

are mobile DNA sequences found in the genome of all organisms; they make up 45% of the human DNA; able to insert into many different locations in the genome

Question 33

how do transposable elements cause mutation

Answer 33

often cause mutation either by direct insertion into gene or by promoting DNA rearrangement such as chromosome deletions, duplication, inversions

Question 34

what are the classes of transposable elements in eukaryotes

Answer 34

retrotransposons and DNA transposons

Question 35

What are retrotransposons

Answer 35

make RNA copies of themselves which are then reverse transcribed into DNA and inserted into chromosome; the RNA is copied into DNA by enzyme reverse transcriptase

Question 36

what do you call the mechanism which retrotransposons transpose

Answer 36

copy and paste, because they leave a copy behind

Question 37

what is the enzyme which is encoded by transposon

Answer 37

transposase

Question 38

what are two types of retrotransposons

Answer 38

LINE and SINE

Question 39

what is LINE

Answer 39

long interspersed elements; have an element which encodes reverse transcriptase but lack LTRs

Question 40

what is SINE

Answer 40

short interspersed elements; are non autonamous LINEs

Question 41

what do you call the most abundant SINE in humans

Answer 41

Alu

Question 42

How do we survive with so much mobile DNA in our genome?

Answer 42

- most transposable elements are found in the introns and therefore are removed during RNA splicing - the vast majority of mobile elements are currently inactive and cannot move or increase in copy number - most are relics and have been inactivated by mutations - some are rendered inactive by host regulatory mechanisms

Question 43

what is the overall frequency of mutation due to class 2 elements in humans

Answer 43

low, 0.2% of all mutations