DNA structure

Question 1

what are the nucleic acids?

Answer 1

DNA and RNA

Question 2

what the the three components of nucleotides?

Answer 2

sugar, an aromatic nitrogenous base, and 1-3 phosphate group

Question 3

DNA includes what type of sugar?

Answer 3

deoxyribose

Question 4

RNA includes what type of sugar?

Answer 4

ribose

Question 5

purines are which bases?

Answer 5

G and A

guanine and adenine

Question 6

pyrimidine are which bases?

Answer 6

C, T, and U
(cytosine, thymine, and uracil)
*mnemonic = CUT the Py

Question 7

which pyrimidine base does DNA use?

Answer 7

thymine

Question 8

which pyrimidine base does RNA use?

Answer 8

uracil

Question 9

nucleosides is a ribose with purine or pyrimidine linked to the?

Answer 9

1’ carbon in a b-N-glycosidic linkage

Question 10

nucleotides are phosphate esters of nucleosides with 1, 2, or 3 phosphate groups joined to the?

Answer 10

ribose ring by the 5’ hydroxy group

Question 11

the building block of DNA is the deoxyribonucleoside 5’ triphosphate (dNTP) where N represents one of the?

Answer 11

four basic nucleosides
(A, G, C, T for DNA)
(A, G, C, U for RNA)

Question 12

the backbone of nucleic acids are the?

Answer 12

sugar and phosphate portion of the dNTP

the base is the variable portion

Question 13

how are nucleotides in nucleic acids covalently linked? location?

Answer 13

by phosphodiester bond between the 3

hydroxy group of he sugar in one nucleotide and the 5’ phosphate group of the sugar in the next nucleotide?

Question 14

nucleotide chains are written in which direction?

Answer 14

5’ to 3’

Question 15

in the oligonucleotide, ACGT, which nucleotide has a free 3’ hydroxy group?

Answer 15

T because it is written last

Question 16

the watson-crick models thats that DNA is in a?

Answer 16

right-handed double helix held together by hydrogen bonds and hydrophobic forces between bases

Question 17

in the cell, DNA is doubled stranded and are in what orientation?

Answer 17

antiparallel, meaning that the 5’ end of one chain is paired with the 3’ end of the other

Question 18

the hydrogen bonds of dsDNA are specific to which nucleotides?

Answer 18

A is always with T
G is always with C
*purine plus a pyrimidine

Question 19

how many hydrogen bonds hold together GC pairs?

Answer 19

three hydrogen bonds

Question 20

how many hydrogen bonds hold together AT pairs?

Answer 20

two hydrogen bonds

Question 21

which component are on the exterior and interior of the double helix?

Answer 21

bases are on the interior

ribose/phosphate backbone on the exterior

Question 22

how are bases stabilized by hydrophobic interactions?

Answer 22

once a purine is H-bonded to pyrimidine, most the polar nature of the individual bases disappears because the charge dipoles are occupied in H-bond

Question 23

genome is the sum total of?

Answer 23

organism’s genetic information

Question 24

each piece of dsDNA is called a?

Answer 24

chromosome

Question 25

prokaryotic genomes are composed of?

Answer 25

single circular chromosome

Question 26

prokaryotes use DNA gyrase enzyme to?

Answer 26

compact their single circular chromosome using ATP to twist the circular molecule by breaking the DNA and twisting the two sides of the circle around each other resulting in dsDNA

Question 27

in eukaryotic genomes, packing is done by wrapping around globular proteins called?

Answer 27

histones

Question 28

after being wrapped around histone and before being completely packed away, DNA has an appearance of beads on a string - those beads are called?

Answer 28

nucleosome and are composed of DNA wrapped around an octamer of histones (group of eight)

Question 29

a fully packed DNA is called?

Answer 29

chromatin

Question 30

when chromosomes are stained, the darker region are more dense and are called?

Answer 30

heterochromatin

Question 31

when chromosomes are stained, the lighter region are less dense and are called?

Answer 31

euchromatin

Question 32

it is known that the euchromatin (lighter regions) have higher rates of?

Answer 32

transcription and therefore higher gene activity because they are less dense so enzymes and proteins are more accessible

Question 33

giemsa stains are used in what lab technqiue?

Answer 33

karyotypes for G-banding patterns

Question 34

centromeres are a region of the chromosomes to which?

Answer 34

spindle fibers attach during cell division via kinetochores

Question 35

centromeres are made up of?

Answer 35

heterochromatin and repetitive DNA sequences

Question 36

metacentric centromere position is when?

Answer 36

centromere is at the center so chromatids are same length

Question 37

submetacentric centromere position is when?

Answer 37

centromere is higher up so that there are short arms (p) and long arms (q)

Question 38

acrocentric centromere position is when?

Answer 38

centromere is even higher up s that the short arms (p) are shorter than in submetacentric and long arms (q) are longer than in submetacentric

Question 39

telocentric centromere position is when?

Answer 39

centromere is so high up that there are no short arm (p) chromatids, only long (q)

Question 40

telomeres are the?

Answer 40

ends of linear chromosomes

Question 41

telomeres are distinguishable by?

Answer 41

repeating unit 6-8 base pairs long and guanine-rich

in many vertebrates: 5’-TTAGGG-3’

Question 42

telomeres function to?

Answer 42

prevent chromosome deterioration and prevent fusion with neighboring chromosomes