DNA + RNA

Question 1

condensed form of DNA: DNA + histones

Answer 1

chromatin

Question 2

core of 8 histone proteins (2x: H2A, H2B, H3, H4) + 2 wraps of DNA

Answer 2

nucleosome core

Question 3

content of histone core protein

Answer 3

+ charged (able to bind to - charged DNA):
lysine
arginine

Question 4

charge of DNA

Answer 4

• charge:

negatively charged phosphate groups

Question 5

histone not in nucleosome core

Answer 5

H1: ties one nucleosome to the next nucleosome

Question 6

AR: deficiency in UMP synthase
↑orotic acid in urine
megaloblastic anemia (can’t make pyrimidines → no DNA synthesis for rapidly dividing RBCs)
DOESN’T cause ↑ammonia

Answer 6

orotic aciduria

Question 7

most common causes of megaloblastic anemia

Answer 7

block THF of pyrimidine pathway:
vitamin B12 deficiency
folate deficiency
block UMP part of pyrimidine pathway:
orotic aciduria (can't be corrected with B12 or folic acid supplements)

Question 8

↑ orotic acid + ↑ ammonia

Answer 8

ornithine transcarbamylase deficiency: urea cycle

Question 9

↑ orotic acid + normal ammonia

Answer 9

orotic aciduria: deficient UMP synthase for pyrimidine synthesis

Question 10

treatment for orotic aciduria

Answer 10

uridine supplementation to allow for pyrimidine synthesis

Question 11

X-linked (mainly boys)
deficient in HGPRT used in purine salvage pathway
can’t salvage GMP or AMP → all purines converted to uric acid

Answer 11

Lesch-Nyhan syndrome

Question 12

HGPRT:
Hyperuricemia
Gout
Pissed off (aggression, self-mutilation “lip-biting”)
Retardation: ID
dysTonia: muscle contractions that distort limbs

Answer 12

Lesch-Nyhan syndrome

Question 13

treatment of Lesch-Nyhan syndrome

Answer 13

treat gout: allopurinol, febuxostat

Question 14

adenosine deaminase deficiency can cause

Answer 14

SCID

Question 15

nucleotide base substitution but final amino acid/polypeptide is unchanged (multiple codons for most amino acids- 3rd base in codon triplet can be variable)

Answer 15

silent DNA mutation

Question 16

nucleotide base substitution changes amino acid sequence so that polypeptide produce has different structural or functional properties

Answer 16

missense DNA mutation

Question 17

nucleotide base substitution results in stop (shortens length of polypeptide)

Answer 17

nonsense DNA mutation

Question 18

nucleotide bases are added or deleted → reading frame is “shifted”
downstream amino acid sequence is completely different

Answer 18

frameshift DNA mutation

Question 19

missense DNA mutation from GAG (glutamic acid) to GTG (valine) in a gene for hemoblogin

Answer 19

sickle cell disease hemoglobin will polymerize → RBC’s sickle

Question 20

2 pyrimidines (usually T-T) on same strand of DNA covalently bonded together → kink in DNA backbone

Answer 20

pyrimidine dimer DNA mutation

Question 21

if a pyrimidine dimer (thymine-thymine) exists in a strand of DNA (and was never repaired) it is susceptible to

Answer 21

UV radiation will damage DNA

Question 22

types of DNA repair

Answer 22

repair single DNA strand:
mismatch repair
nucleotide excision repair
base excision repair
repair double strand:
nonhomologus end joining

Question 23

wrong base added to daughter (C-T) strand during replication

cut daughter strand upstream → remove bases → redo DNA replication

Answer 23

mismatch repair

Question 24

correct DNA replication but damaged later (UV radiation - pyrimidine dimers)
remove large, BULKY area of nucleotides via endonucleases (cut both sides)→ DNA poly fills gap → DNA ligase join fragments

Answer 24

nucleotide excision repair

Question 25

remove NONBULKY damage (only 1 base damaged)
glycosylase: recognizes base and removes the base
endonuclease: cuts DNA and removes sugar
DNA poly ß: fills gap
DNA ligase: seals

Answer 25

base excision repair

Question 26

clean break in both strands of DNA - bring together 2 ends of DNA fragment

Answer 26

nonhomologus end joining

Question 27

disease with mutation in gene that codes for a mismatch repair protein

Answer 27

hereditary nonpolyposis colorectal cancer

Question 28

disease with defective nucleotide excision repair: can’t repair pyrimidine dimers due to UV radiation

Answer 28

xeroderma pigmentosum

↑ risk of skin cancer: melanoma, BCC, SqCC

Question 29

mutation of helicase → defective DNA replication + repair

Answer 29

bloom syndrome

hypersensitive to sunlight
↑ risk of: leukemia, lymphoma, immunodeficiency, infertility

Question 30

disease due to defective repair of dsDNA breaks

Answer 30

ataxia telangiectasia
IgA deficiency
cerebellar ataxia
poor smooth pursuit
↑AFP >8 mo
sensitive to ionizing radiation → can't repair DNA damage

Question 31

disease due to defective repair of dsDNA breaks

Answer 31

BRCA1 and BRCA2 mutations:

breast cancer + ovarian cancer

Question 32

RNA copied from DNA template and translated into proteins

Answer 32

mRNA

Question 33

transfers information from mRNA and brings in amino acids to form polypeptide chain

Answer 33

tRNA

Question 34

largest type of RNA

Answer 34

mRNA

Question 35

smallest type of RNA

Answer 35

tRNA

Question 36

part of ribosome

binds amino acids together

Answer 36

rRNA (ribosomal)

Question 37

most abundant type of RNA

Answer 37

rRNA

Question 38

synthesis of mRNA + tRNA

Answer 38

nucleoplasm (liquid part of nucleus)

Question 39

synthesis of rRNA

Answer 39

nucleolus

Question 40

first mRNA codon to be translated into an amino acid at the beginning of a polypeptide chain

Answer 40

AUG: start codon

amino acid in eukaryotes: methionine

Question 41

mRNA stop codons: tells ribosome that polypeptide sequence is done with translation

Answer 41

UGA
UAA
UAG

Question 42

enzyme that transcribes DNA into mRNA

Answer 42

RNA polymerase

Question 43

mRNA → amino acids

Answer 43

translation