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Grade 12 bio > DNA > Flashcards

Flashcards in DNA Deck (63)
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1
Q

What are the three main components of a neucleotide

A

deoxyribose sugar
phosphate group
nitrogenous base

2
Q

What are the four different nitrogenous bases

A

Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)

3
Q

Explain Chargoff’s rule

A

in a single given sample of DNA…

  • proportion of A will be same as T
  • proportion of G will be same as C
4
Q

what does it mean to be antiparallel

A

one strand will be directed from 3’ to 5’
the other will be from 5’ to 3’
opposites

5
Q

how are the 3’ and 5’ ends different

A

3’ end had a free OH group on the 3rd carbon on the sugar

5’ end has a phosphate group attached to the 5th carbon on the sugar

6
Q

is DNA conservative, semi-conservative or dispersive

A

semi-conservative

7
Q

what does gyrase do

A

relieves any tension from the unwinding strands

8
Q

what does DNA helicase do

A

unwinds the double helix (breaks the H-bonds between base pairs)

9
Q

what does SSBP do

A

binds to the exposed strands and stop them from reattaching (annealing)

10
Q

what does RNA primase do

A

lays down primers on each parent strand to make starting point

11
Q

what does DNA polymerase III do

A

adds complimentary nuceleotides to the new, growing strands

12
Q

what does DNA polymerase I do

A

removes the primers that RNA primase put down and replaces them with the correct nucleotides

13
Q

which three enzymes aid in DNA strand separation

A

Gyrase
DNA helicase
SSBP

14
Q

what is the purpose of DNA and RNA

A

direct the growth and development of every living thing by means of a chemical code

15
Q

what is DNA and RNA made up of

A

nucleotides

16
Q

what is mispairing

A

new nucleotides mispair with another on template strands

ex. T goes with G instead of A

17
Q

what is strand slippage

A

additions or emissions of nucleotides
if a neucloetide slips out on the template strand, the newly synthesized strand will be made missing one of the neuclotides- completely altering the genetic code
if a neucleotide slips out on the synthesized strand, a new one will be added to ensure the balance is regained- but when it goes on to become a template strand, the syntehsized strand from that will have an extra nucleotide also altering the code

18
Q

how are errors in DNA replication corrected

A

DNA polymerase II proofreads the new DNA, identifying any errors.
if one is found, replication stalls
DNA polymerase I corrects the error
DNA replication continues

19
Q

how often does the correction of errors in DNA replication work

A

99% of the time

20
Q

where does transcription occur

A

in the nucleus

21
Q

where does translation occur

A

in cytoplasm on ribosomes

22
Q

what are the three types of RNA

A

mRNA- messenger RNA
tRNA- transfer RNA
rRNA- ribosomal RNA

23
Q

what is mRNA

A

messenger RNA

forms a code (sequence of bases)

24
Q

what is tRNA

A

transfer RNA

uses mRNA to link amino acids

25
Q

what is rRNA

A

ribosomal RNA

structural component of ribosomes

26
Q

what are codons

A

sequence of 3 bases in mRNA
codes for a specific amino acid
some are “start” and “stop” codons

27
Q

what does RNA polymerase do

A

reads the coding strand and arranges mRNA accordingly

28
Q

what does the promotor region do

A

moderates the speed of transcription

high in A-T and T-A

29
Q

what is transcription (vague)

A

DNA to mRNA

30
Q

describe the initiation phase of transcription

A

RNA polymerase binds to DNA next to one of its start codons in the promotor region
opens up the helix- exposing the template strand

31
Q

describe the elongation phase of transcription

A

RNA polymerase starts adding nucleotides together using the template strand to match the correct base
this occurs in the 5’ to 3’ direction

32
Q

explain the termination phase of transcription

A
RNA polymerase reaches the end of the gene (a terminator sequence)
transcription stops
mRNA separates from the DNA
DNA double helix reforms
mRNA is modified
33
Q

how it mRNA modified during the termination phase of transcription

A
  • a 5’ cap added to start
  • poly-A tail added to end
  • introns cut out (splicing)
34
Q

what is an intron

A

non-coding region of DNA

35
Q

what is an exon

A

a coding region of the DNA

36
Q

what is a mutation

A

a permanent change in the nucleotide sequence of a cells DNA

37
Q

what is a single gene mutation

A

a mutation that involves changes in the nucleotide sequence of one gene

38
Q

what is a point mutation

A

a mutation involving a single base pair substitution, insertion or deletion

39
Q

what is a frameshift mutation

A

a mutation caused by the deletion or addition of a number of nucleotides not divisible by 3, resulting in a change of the reading frame

40
Q

what is a silent mutation

A

a mutation that doesn’t change the amino acid sequence of a protein

41
Q

what is a missense mutation

A

a mutation that changes the amino acid sequence of a protein

42
Q

what is a chromosome mutation

A

a mutation that involves changes in chromosomes and may involve many genes

43
Q

example of the chromosomal mutation: deletion

A

abCDEFgh TO abgh

44
Q

example of the chromosomal mutation: inversion

A

abCDEfgh TO abEDCfgh

45
Q

example of the chromosomal mutation: duplication

A

aBCDefgh TO aBCDBCDefgh

46
Q

example of the chromosomal mutation: translocation

A

abcdefgh TO abcdMNOP

IJKLMNOP TO IJKLefgh

47
Q

is tRNA or mRNA linear

A

tRNA is not linear

mRNA is linear

48
Q

explain the structure of tRNA

A

single strand of mRNA that has folded back on itself

contains an anticodon on one end and an amino acid on the other

49
Q

translation represents going from what

A

mRNA and tRNA to proteins

50
Q

transcription represents going from what to what

A

DNA to mRNA

51
Q

explain the initiation phase of translation

A
  • ribosomal sub-unit attaches to the mRNA near the start codon (AUG)
  • the first tRNA carrying mathionie is the initiator tRNA with a VAC anticodon
  • tRNA enteres the psite (bringing the appropriate amino acid)
  • a second tRNA enters the asite bringing another amino acid
  • peptide bonds form between the two amino acids
  • ribosome shifts over and original tRNA moves to esite
52
Q

explain the elongation phase of translation

A
  • third tRNA enters asite and peptide bonds form between amino acids again
  • after the esite the tRNA will go out to the cytoplasm again
  • this continues until the ribosome reaches a stop codon
53
Q

put nucleotide, gene, codon, chromosome, nucleotide base, DNA, nucleus

A

nucleotide base, nucleotide, codon, gene, DNA. chromosome, nucleus

54
Q

what is negative gene regulation?

A

the signaling molecules do not interact directly with the genes

55
Q

what is positive gene regulation?

A

a signaling molecule generates a complex that interactes directly with the DNA (common in eukaryotes)

56
Q

what do histones do?

A

they wrap up in DNA, preventing certain genes from being expressed
polymerase cannot reach it- doesn’t become mRNA

57
Q

what was Friedrich Miescher contributions

A

“Discovered” the nucleic acid by isolating the nucleus of white blood cells taken from the pus bandages from a hospital.

58
Q

what were Phoebus Levene ‘s contributions

A

discovered the difference between what is now DNA and RNA
also correctly stated what nucleotides are made up of
He suggested the idea that nucleic acids are long chains of nucleotides- which was later proved to be correct.

59
Q

what were Oswald Avery, Colin MacLeod, Maclyn McCarty ‘s contributions?

A

They confirmed that DNA was in fact a hereditary material.

60
Q

name three individuals and their contributions to genetics

A

depends on which i choose

answers may vary

61
Q

what were Linus Pauling’s contributions

A

Developed 3D models of miniscule biological materials based on known distances and bond angles. He also discovered that many proteins have a helix shape.

62
Q

what were Rosalind Franklin’s contributions

A

Used x-ray diffraction to analyze the structure of biological molecules. Franklin concluded that DNA has a defined helix structure. She also learned lots about the general structure of DNA altogether. The nitrogenous bases are located inside the helix, the sugar-phosphate backbone was on the outside.

63
Q

what were Francis Crick, James Watson ‘s contributions

A

Using information taken from other scientists, they assembled a model of DNA which is now recognized as the molecular structure of DNA