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Biology Higher Level > 7.1 > Flashcards

7.1 Flashcards

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1
Q

what did hershey and chase discover?

A
  • they discovered that dna was the genetic material instead of protein
  • proved that dna makes up genes within an organism
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2
Q

describe the 5 steps to hershey and chase’s experiment

A
  1. make (cultured) a virus in radioactive phosphorus (found in dna) and sulphur (found in protein coat)
  2. expose bacteria (e-coli) with this virus
  3. centrifuge to separate the protein coat to the top (fluid supernatant of matrix) and bacteria to the bottom (solid pellet of bacteria)
  4. measure the radioactivity with a geiger counter
  5. found that sulphur was mostly found in the supernatant and high phosphorus radioactivity is seen in the bottom (within cells), indicating dna, which must be the genetic material
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3
Q

how are nucleosomes bound together?

A

by a small length of dna and binding of the N-terminal tails of histone proteins

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4
Q

what is the function of the H1 histone protein?

A

its function is to hold the coiled dna in place around the histone protein core

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5
Q

how does dna supercoil?

A

by bunching up nucleosomes close together

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6
Q

in which direction does dna replication occur?

A

5’ to 3’

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7
Q

describe the 7 steps of dna replication

A
  • a semi conservative process
    1. dna gyrase unwinds dna
    2. helicase splits the dna into 2 separate strands
    3. dna primase adds rna primers on the lagging strand
    4. dna polymerase III adds nucleotides in a 5’ to 3’ direction continuously on the leading strand but discontinuously on the lagging strand
    5. okazaki fragments form on the lagging strand
    6. dna polymerase I replaces rna primer with dna
    7. dna ligase joins the okazaki fragments together
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8
Q

what is the function of dna gyrase during dna replication?

A

unwinding the 2 strands

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9
Q

what is the function of helicase in dna replication?

A

splitting the dna strand into 2 template strands

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10
Q

what is the function of the single stranded binding proteins during dna replication?

A

to hold the 2 template strands apart, and in place so they dont wind back together

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11
Q

what is the function of dna primase during dna replication?

A

to add rna primer to the lagging strand

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12
Q

what is the function of dna polymerase III during dna replication?

A

add nucleotides in 5’ to 3’ direction continuously on the leading strand and discontinuously on the lagging strand

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13
Q

what are okazaki fragments?

A

sections of replicated dna between rna primer formed as a result of discontinuous replication on the lagging strand

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14
Q

what is the function of dna polymerase I during dna replication?

A

to replace rna primer nucleotides with dna nucleotides

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15
Q

what is the function of dna ligase during dna replication?

A

to bind okazaki fragments together

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16
Q

what are ddNAs?

A
  • dideoxyribonucleic acid
  • nucleotides that do not follow further nucleotide addition due to their structure
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17
Q

describe the 4 steps of sanger sequencing

A
  1. replicate dna with ddNA nucleotides base A, normal nucleotides and dna polymerase
  2. repeat process for each remaining base (c, g and t)
  3. the ddNA blocks replication at varying lengths, so they can be separated by gel electrophoresis
  4. this forms a sequential banding pattern
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18
Q

what are the types of base sequences?

A
  1. coding
  2. non-coding
19
Q

what are non-coding sequences useful in?

A

regulating gene expression, introns, telomeres, trna and rrna genes

20
Q

how are non-coding sequences useful in regulating gene expression?

A

promotes or represses transcription of adjacent coding sequences

21
Q

how are non-coding sequences useful in introns?

A

they aid mrna processing from within the coding sequence but are spliced out before translation

22
Q

how are non-coding sequences useful in telomeres?

A

they are repetitive sequences at the end of chromosomes to make sure coding sequences aren’t lost during replication

23
Q

how are non-coding sequences useful in trna and rrna genes?

A

they are sequences who’s transcription produces trna for translation or rrna to form ribosomes

24
Q

what is the full name of rrna?

A

ribosomal ribonucleic acid

25
Q

what did hershey and chase use in their experiment?

A
  • by taking viruses that are known as ‘T2 bacteriophage’
26
Q

describe the fucntion and structure of a T2 bacteriophage

A
  • a protein coat
  • a capsid head containing dna
  • known to inject genes inside cells
27
Q

why are some sulphur present in the solid pellet and some phosphorus present in the supernatant in hershey and chase’s experiment?

A
  • agitation of the solution shakes of many of the protein coats into the supernatant
  • but some may remain attached to bacteria and end up in the pellet
  • some viruses may not inject their dna into the bacteria as well, meaning that it remains in the supernatant
28
Q

what are the 2 groups of complementary bases?

A
  1. purine
  2. pyrimidines
29
Q

which 2 bases are found under the purine group?

A
  1. adenine
  2. guanine
30
Q

which 3 bases are found under the pyrimidine group?

A
  1. thymine
  2. cytosine
  3. uracil
31
Q

what does eukaryotic dna wrapped around?

A

8 histone proteins

32
Q

what does the rod histone do?

A

clamps the dna in position

33
Q

what are the components of a nucleosome and what is the function of it?

A
  • eukaryotic dna
  • 8 histone proteins
  • a rod protein
  • fxn: allows dna to supercoil
34
Q

why are prokaryotic dna ‘non-protein associated’ aka naked?

A

because it does not wrap around histones

35
Q

what is dna profiling?

A

the process by which small repeat nucleotide sequences (coded for by a single allele named tandem repeats) are used to identify individuals

36
Q

what are variable tandem repeats?

A

since tandem repeats repeat a varying number of times, in different individuals, it creates a unique dna pattern

37
Q

describe the 4 steps of dna profiling

A
  1. collection and amplification of dna with PCR
  2. the strands are cut with restriction enzymes
  3. separated with gel electrophoresis
  4. pattern comparison for similarities
38
Q

what can dna profiling be used for? give 2 examples

A
  1. paternity or maternity testing
  2. to assess the likelihood of their involvement in the crime
39
Q

what is sanger sequencing?

A

the determination of entire dna base sequence

40
Q

what is the difference between sanger sequencing and dna profiling?

A

sanger sequencing is…
- far more costly
- due to sequencing of entire genome instead of just the tandem repeats

41
Q

what must not happen before sanger sequencing can occure?

A
  • requires dna replication to be prevented, so it does not interrupt the process
42
Q

how is dna replication prevented in the process of base sequencing?

A
  1. dna is mixed with ddNA nucleotides
    - because ddNAs do not contain an OH carbon on the 3’ carbon
    - meaning that no other nucleotides can attach to the 3’ end
  2. therefore, it halts dna replication at ddNA bases
43
Q

what is bioinformatic analysis?

A

large storage and analysis of gene sequences on computers

44
Q

what are the several key advancements in medical science departments that bioinformatics analysis has helped with?

A
  1. identification of similarities within genes for people who suffer from genetic disorders informing diagnostic tests
  2. comparison of genes to other organisms with alternative forms of a disorder, despite similar genes despite mutation

Biology Higher Level (50 decks)

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