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lec 6 dna and flow of genetic info Flashcards

1
Q

what is DNA?

A

genetic/molecular code that is blueprint for living things

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2
Q

what is the shape of DNA?

A

double helix

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3
Q

what are the components of DNA?

A

two strands of nuleotides held together by base pairing

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4
Q

what type of bonds hold bases together?

A

hydrogen bonds

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5
Q

can all bases pair with each other? if not, explain

A

no
-adenine+thymine
-cytosine+guanine

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6
Q

differences in DNA sequence leads to…

A

genetic variation

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7
Q

different gene sequences are caused by..
what scientific process is this the basis for?

A

-different arrangements of A, T, C, G
-forensic identificaion

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8
Q

when does DNA replication occur?
what are the steps of DNA replication?

A

Occurs during S phase of the cell cycle

  1. Hydrogen bonds broken, parent strands separate
  2. DNA polymerase attaches to parent strand, makes new strand by adding together nucleotides which compliment the sequence of the parent strand
  3. Two final DNA strands are half new and half old (parent and daughter strand)
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9
Q

what is the rate of error when placing nucleotides? what can reduce error rate, by how much?

A

1/10 000

DNA polymerase proofreads
1/1mil

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10
Q

if DNA proofreading fails, what occurs?

A

mismatch

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11
Q

what can FURTHER reduce error rate after mismatch occurs? by how much?

A

mismatch repair enzymes
1/1bil

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12
Q

if a mismatch is NOT corrected, what occurs?

A

mutation; permanant error in DNA sequence

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13
Q

what are the 3 steps of DNA repair? breifly explain each

A
  1. recognition: damaged area detected
  2. removal: region removed by enzymes
  3. replacement: DNA polymerase fills gap
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14
Q

DNA repair is essential for..?

A

normal gene fxn

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15
Q

what are 3 causes of DNA mutation?

A
  1. UV light
  2. ionizing radiation
  3. chemicals (free radicals) { molecule w/ 1+ unpaired electron in outer shell}
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16
Q

diseases result from..?

A

failed DNA repair mechanisms

17
Q

briefly describe what a gene is in terms of DNA and RNA

A

gene is sequence of DNA that is used to make copy of RNA molecule used to make proteins

18
Q

simply put, what is the process resulting in proteins

A

DNA-> RNA -> proteins

19
Q

what are 3 main differences of RNA when compared to DNA?

A

RNA:
1. single stranded
2. uracil replaces thymine
3. uses sugar ribose instead of deoxyribose

20
Q

what are the 3 types of RNA? what are they all made from?

A

1.messenger RNA (mRNA)
2. ribosomal RNA (rRNA)
3. transfer RNA (tRNA)

all made from DNA

21
Q

what does each type of RNA do?

A
  1. mRNA:
    -specifies order of amino acids in protien using codons (3 bases)
    -diff amino acids specified by codons
  2. rRNA:
    -major component of ribosomes
    -link AA using covalent bonds
  3. tRNA:
    -transports correct AA to ribosome
22
Q

what are the two steps to make proteins? briefly describe each step.

A
  1. transcription :
    -produces mRNA from DNA
    -mRNA moves from nucleus-> cytoplasm
  2. translation :
    -assembles AA of protiens using mRNA
23
Q

what enzyme creates mRNA?

A

RNA polymerase

24
Q

what happens during transcription?

A

RNA polymerase…
1.binds to region of DNA called promoter (start codon)

  1. unwinds DNA
  2. reads DNA, then adds complimentary nucleotides to mRNA
  3. stops when terminator region is read
    -RNA polymerase+mRNA detatch from DNA
25
Q

a similar process to transcription is used to make..?

A

rRNA and tRNA

26
Q

what are 4 differences between transcription and DNA replication?

A

in transcription..

  1. one strand used as template
  2. product : single stranded RNA not double stranded DNA
  3. GENES are transcribed to RNA not entire DNA
  4. transcription constant, replication only before division
27
Q

sequence of 3 nucleotides in mRNA specifies..? what are the groups of 3 nucleotides called?

A

order of amino acids

codon

28
Q

t/f more than one codon can code for a specific amino acid

29
Q

what is the start codon?
the 3 possible stop codons?

A

start: AUG

stop: UAA, UAG, UGA

30
Q

what are the 4 things needed for the construction of a protein?

A
  1. mRNA molecule
  2. Ribosomes (rRNA+proteins)
  3. Amino acids
  4. tRNA
31
Q

what is tRNA? what are 2 things it carries?

A

RNA molecule folded on itself

carries:
-anticodon (complimentary to DNA codon)
-corresponding amino acid

32
Q

what is the process of tRNA?

A
  1. brings correct anticodon +AA
  2. anticodon links to DNA
  3. AA covalently linked to next AA brought (ribosome covalently links AA)
  4. after AA attatched, tRNA + anticodon detatch
33
Q

sickle cell anemia is an example of..?

A

a mutation

34
Q

sickle cell anemia is when the shape of the hemoglobin protein in red blood cells is shaped as a sickle (half moon) instead of a disc, what is this caused by?

A

single nucleotide mutation in hemoglobin gene

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