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biomolecular science > DNA > Flashcards

DNA Flashcards

1
Q

describe the genome of a prokaryote

A

circular genome - often one or many (only rarely linear) - found within the nucleoid region of the bacterial cell

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2
Q

what is supercoiling of prokaryotic DNA and what is the difference between positive and negative supercoiling

A

supercoiling is the tight twists and loops prokaryotic DNA makes in order to become circular without the need for histones - positive is due to an additional extra turn in the double helix and negative is the removal of a turn

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3
Q

what are the nucleoids in prokaryotes anchored by

A

protamine

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4
Q

what is a gene

A

a sequence of DNA or RNA that codes for a molecule (protein) that has a function

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5
Q

what is an intron and exon section of a gene

A

non-coding and coding regions

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6
Q

what is a pseudogene

A

a gene sequence with no transcription

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7
Q

what is a tandem repeat in a gene sequence

A

a section of the sequence that is repeated immediately

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8
Q

what are the two kinds of genome wide repeats

A

retrotransposon and transposon

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9
Q

describe the genome of a eukaryote

A

eukaryotes have linear chromosomes and almost all cells are diploid with one set of chromosomes from each parent

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10
Q

how are eukaryotes chromosomes packed

A

linear chromosomes are bound to charged protein complexes called histones

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11
Q

describe mitochondrial DNA (mtDNA)

A

small, circular DNA located in the mitochondria to provide genes for mitochondrial function and tRNA/rRNA

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12
Q

name 3 differences mtDNA/ cpDNA have when compared to DNA

A
  1. faster mutation rate (only mtDNA)
  2. low variation due to uni-parental inheritance
  3. useful in species identification
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13
Q

name the main difference between mtDNA and cpDNA

A

cpDNA is much larger than mtDNA

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14
Q

briefly sum up eukaryotic DNA

A

Eukaryotic nuclear DNA is found within the nucleus and is condensed in to a number of higher order structures.

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15
Q

what does DNA stand for

A

deoxyribonucleic acid

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16
Q

what is DNA made up of

A

a double helix
base pairs
genes
A, T, G, C

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17
Q

how does DNA store its information

A

in a series of base pairs that code for different amino acids to later create proteins

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18
Q

how does DNA protect its information

A

the tight wounding of its double helix as well as an encasement in a protective membrane

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19
Q

describe DNA on a chemical level

A

nucleotides joined together via phosphodiester bonds to form the sugar-phosphate backbone, and nitrogenous bases joined via hydrogen bonds to form anti-parallel DNA strands

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20
Q

what are DNA nucleotides made up of

A

a pentode sugar, nitrogenous bases and a phosphate group

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21
Q

what makes DNA DEOXYribonucleic acid

A

the second carbon on the pentose sugar in each nucleotide is missing an oxygen molecule

22
Q

what is the difference between ATP, ADP and AMP

A

the number of phosphate groups attached

23
Q

what is the difference between a nucleoside and a nucleotide

A

a nucleoside does not include the phosphate group whereas a nucleotide does

24
Q

what are the two main differences between DNA and RNA

A
  1. the sugar molecules are different
  2. RNA contains uracil in replacement for thymine
25
describe the structure of double stranded DNA
two strands of nucleotides running antiparallel (5'-3' direction) that are bonded via hydrogen bonds between opposite bases
26
what is the difference between the joining of adenosine and thymine when compare to cytosine and guanine
A and T join by 2 hydrogen bonds whereas C and G join by 3
27
how was the double helix of DNA discovered
by X-ray diffraction of DNA by Maurice Wilkins and Rosalind Franklin exposed a helical structure and the double part was later discovered by James Watson and Francis Crick
28
how many bases in each turn of the helix
10
29
what gives DNA its stability
once the bases bond to each other they stack almost on top of each other creating a hydrophobic effect and van der waals forces between bases, providing stability
30
name 3 reasons why the double helix of DNA may be split into singular strands
1. the transcription process into mRNA 2. the copying of the DNA strand during replication 3. the copying of DNA molecule during PCR
31
how do we artificially separate DNA strands
the process of melting - high temperature to break the hydrogen bonds
32
how are hairpin loops formed in RNA strands
self-complementary regions join together creating the loops with random coil
33
what are the main three types of RNA and what do they generally do
Messenger RNA (mRNA) - active during transcription as they code for proteins specific to a gen by being complementary to a template strand of DNA Transfer RNA (tRNA) - the physical link between mRNA and an amino acid Ribosomal RNA (rRNA) - forms ribosome with protein (only active during translation)
34
what are molecular markers
a loose term to describe a specific piece of DNA that gives a unique piece of information
35
what are the three main molecular markers used
gene regions SNPs - single nucleotide polymorphisms STRs
36
briefly describe the molecular marker; gene regions
where an entire gene or part of a gene sequence is marked - helpful because typically we have to visualise to entire gene sequence to identify variable sites.
37
using gene region molecular markers in nuclear genetic sequences is good for what
identifying different gene as their is little variation e.g. body fluid identification
38
using gene region molecular markers on mtDNA is good for what
identifying a difference between species due to more variation being seen e.g. wildlife forensics
39
what can SNP molecular markers do and how do they do it
SNPs occur through mutation events in the triplet codes of a base sequence and they can tell us very informative things like the colour of that persons eyes
40
why are there two copies of STRs for each chromosome pair
as they are inherited in a mendelian fashion - one from each parent
41
what is the difference between heterozygote and homozygote STRs
hetero = fragments are different sizes homo = fragments are the same size
42
name the 6 methods we use for DNA detection
PCR - polymerase chain reaction Fluorescence detection Fragment length analysis DNA sequencing qPCR Melt curve PCR
43
why is PCR so important in DNA detection and analysis
as its the basis of all DNA detection approaches as it increases the number of copies of the molecularly marked DNA
44
why is fluorescence detection important
as DNA cant be observed directly
45
explain how DNA is detected via fluorescence through the use of agarose gel
DNA is negatively charged and run through a matrix - this allows the DNA to separate according to its relative mobility through the matrix, meaning that small bands will travel further and larger bands not so much. We can identify these bands using a known fragment size ladder, via the use of staining with intercalating dye found within the agarose gel
46
why do we use fragment length analysis in DNA detection
as the sizing accuracy is better than that with fluorescence detection and it can also be used to detect STRs
47
briefly describe the method of DNA sequencing
○ First PCR produces DNA fragment ○ Second (sequencing) PCR adds fluorescent ○ Results in multiple different length DNA strands ○ Each strand has different terminal coloured dye
48
what is qPCR
the combined principles of PCR and agarose gel so that the fluorescence is detected as DNA is amplified
49
describe melt curve PCR
uses the same PCR instrument but fluorescence is detected at the end of PCR to detect gene regions and SNPs
50
explain the method of melt curve PCR in DNA detection and give an example
○ Fluorescent probes bind to all the dsDNA that has been produced ○ The probe fluoresces when bound ○ The mix is then heated ○ At a specific temperature the probe 'melts' away from the DNA ○ A reduction in fluorescence is observed - used in body fluid identification

biomolecular science (14 decks)

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