Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology > Unit one DNA and the Genome > Flashcards

Unit one DNA and the Genome Flashcards

1
Q

state the possible functions of the non-coding sequences.

A

regulate transcription
and
non-translated forms of RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

explain what is meant by a gene

A

a gene is a small section of DNA on a chromosome that codes for a particular sequence of amino acids to make a specific protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe what is meant by the genome

A

the genome of an organism is its entire hereditary information encoded in DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe the structure of the genome

A

the genome is its entire hereditary information encoded in the DNA, within it there are exons and introns. DNA sequences that code for proteins are called genes some non-coding sequences are to regulate transcription and some are transcribed but not translated. Non-translated forms of RNA include tRNA and mRNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

give an account of the structure of a DNA molecule

A

double helix
strands composed of nucleotides
nucleotides are made up of phosphate, deoxyribose sugar, and a base.
complementary base pairing
anti-parallel strands
each chain has a deoxyribose at the 3’ end and a phosphate at the 5’ end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

draw and clearly label a DNA nucleotide

A

phosphate 5’

deoxyribose sugar 3’

base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe the bonds involved in holding the nucleotides together and the bonds that hold the chains together.

A

Deoxyribose sugar and phosphate are connected by the sugar phosphate bond, that connects the 5’ phosphate to the 3’ deoxyribose sugar, this creates a poly-nucleotide chain.

The bases are connected to each other by hydrogen bonds, the base must be connected to the complementary other such as A=T , C=G.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

compare the organisation of DNA in prokaryotic and eukaryotic cells

A

prokaryotes lack a nucleus, and the DNA is a large circular double stranded chromosome, some may have an extra plasmid and the large chromosome are supercoiled. Whereas eukaryotes have a nucleus, and the DNA is arranged in a linear double possess mitochondrial and chloroplast DNA and the DNA wraps around histone proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

describe the differences between prokaryotic and eukaryotic cells

A

circular chromosomes DNA in prokaryotic cells

plasmids in prokaryotic cells

plasmids in yeast

linear chromosomes DNA in eukaryotic cells

plasmids in chloroplast and mitochondrion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe the replication of the leading strand of DNA

A

after the hydrogen bonds break, the DNA. unzips

a DNA primer attaches to the start of the piece of DNA being copied.

DNA polymerase then attaches free nucleotides to the 3’ end of the primer

this is a continuous process until the leading strand is copied.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

give an account of the replication of a molecule of DNA

A

DNA uncoils and unzips, the primers bind at the 3’ end of the DNA strand. DNA polymerase adds complementary DNA nucleotides to to the 3’ end of the primer molecule. The primer binds to the lagging strand in fragments. The fragments are joined by DNA ligase. Replication occurs at several points on a DNA molecule at the same time. Replication of DNA requires energy (ATP).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe the main steps in PCR.

A

DNA is heated to 92-98 degrees celsius to denature DNA and break the hydrogen bonds, it is then cooled to 50-65 degrees celsius to allow the primer to bind to the target sequence. Primers are complementary to the 3’ end of the DNA strands. DNA is re-heated to 70-80 degrees celsius to allow heat tolerant DNA polymerase to replicate the primed regions, the repeated cycles of heating and cooling amplify the regions of DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe the role of the enzyme in DNA replication

A

DNA polymerase adds DNA nucleotides to the 3’ end and can only add them in one direction. DNA ligase is used to join the fragments on the lagging strand, this means the leading strand is replicated continuously whilst the lagoon strand is replicated discontinuously in fragments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

give examples of practical applications of PCR

A

solves crimes

disease detection

paternity suits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

explain why a heat tolerant DNA is required

A

so it will not denature because of the high-temperature allowing it to add DNA nucleotides to the growing strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

describe what happens at each of the 3 stages of PCR.

A

1) DNA is heated to 92-98 degrees for a few seconds to allow DNA to denature and the strands to separate.
2) DNA is then cooled to 50-65 degrees to allow the primers to bind to the target sequence of the separate strands
3) DNA is heated again to 70-80 degrees for a few minutes, allowing heat-tolerant DNA polymerase to copy the DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

state the temperature for each of the three stages in PCR

A

stage 1 = 92-98

stage 2 = 50-65

stage 3 = 70-80

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

describe what is meant by PCR

A

The polymerase chain reaction allows specific sections of DNA to be amplified in vitro.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

describe the role of ligase

A

the enzyme ligase joins the fragments of DNA nucleotides together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Explain why one strand is called the lagging strand and one strand is called the leading strand.

A

The leading strand is copied in a continuous process, whereas the lagging strand is copied in a discontinuous process of fragments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

describe the stages of DNA replication

A

after the hydrogen bonds break, the DNA unzips and unwinds. A DNA primer attaches to the start of the piece of DNA being copied. DNA polymerase then attaches free nucleotides to the 3’ end of the primer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

state which end of the primer the nucleotides are added during replication.

A

3’ end of a primer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

explain the role of a primer

A

provides a starting point for DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

name the enzyme used to copy DNA

A

DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
define what is by a mutation
mutations are spontaneous and random changes in the DNA that can result in no protein or an altered protein being synthesised.
26
name the 3 types of single-gene mutations and explain the impact of each of the mutations on the amino acid sequence.
deletion - changes every amino acid AFTER the deletion insertion - changes every amino acid AFTER the insertion substitution = silent - amino acid stays the same missense - changes 1 amino acid nonsense - early stop codon
27
for substation mutations explain the impact of each missense, nonsense and splice-site mutations
missense - changes 1 amino acid nonsense - early stop codon splice-site - some introns are kept and some axons are not included in the mature transcript.
28
name the 4 type of chromosomes structured mutations
duplication deletion inversion translocation
29
explain what happens in each of the 4 types of chromosomes structure mutations
duplication - a section of a chromosome is added from its homologous partner deletion - a section of a chromosome is removed inversion - a section of chromosome is reversed translocation - a section of a chromosomes is added to a non-homologous chromosome.
30
explain how mutations can lead to evolution
Mutations creates new DNA sequences for a particular gene, creating a new allele. This allows mutated species to survive and avoid old threats and dangers. Explain how duplication mutations In particular can aid evolution
31
name and describe the types of structural mutations of chromosomes
deletion involves the loss of a gene. Translocation, involves a section of a chromosome attaching to another. Duplication, involves genes being copied within the chromosome. Inversion, involves the section of a chromosome is reversed.
32
describe single gene mutations
single gene mutations are spontaneous and random changes in DNA. substitutions means a base is substituted by another. Insertion means an extra base is added. Deletion means a base is lost. Both insertion and deletion result in a frameshift mutation meaning on change in every amino acid after the insertion or deletion. Single gene mutations are important for evolution. And splice-site mutations can alter the mature transcript.
33
explain chromosome mutations
chromosome mutations can involve changes to the chromosomes structure. deletion, involves the loss of a gene. Duplication involves genes being copied within the chromosomes. Inversion, involves the section of a chromosome is reversed.
34
give an account of stem cells, therapeutic uses of stem cells and ethical issue surrounding their use
stem cells are unspecialised cells, they can divide to form new stem cells or differentiate into specialised cells can be used to treat diseased organs or tissues for example skin grafts and bone marrow transplants. However, some people believe extracting embryonic stem cells is the equivalent to ending someones life therefore should not be used for research.
35
describe the type of stem cells and their properties
stem cells are unspecialised cells in animals, they can divide to form more new stem cells or can differentiate into specialised cells for specific functions. The 2 types of stem cells are tissue stem cells or embryonic stem cells. Embryonic stem cells can differentiate into any specialised cells (pluripotent). Tissue stem cells have narrower differentiation potential and can only differentiate into specialised cells found in the specific tissues (multipotent).
36
give an account of cell differentiation in plant and animal cells
cells become specialised in structure or properties, and genes are expressed by producing the characteristics of that cell. In plant specialised cells from meristem cells, meristems are found in the root tip or shoot tip.
37
explain the ethical issue surrounding the use of embryonic stem cells for research
some people believe an early embryo is classified as a human and therefore the removal of stem cells is equivalent to ending a human life. other believe that carrying out research using stem cells is helping to treat disease such as cancers.
38
what properties of embryonic stem cells make them useful for research purposes
embryonic stem cells in all genes have the potential to be switched on and off, therefore they can differentiate into any types of cell in the human body.
39
describe how stem cells can be used in research
stem cells tell us about cell growth, differentiation and how gene regulation works, they can be used model cells to study how diseases develop or for drug tests.
40
give examples of therapeutic uses of stem cells
skin grafts for burns corneal transplants
41
Explain what is meant by multipotent and which stem cells shows this ability
Tissue stem cells are multipotent this means they can only differentiate into some special cells, as they have a narrower differentiation potential.
42
explain what is meant by pluripotent and which stem cells shows this ability
Embryonic stem cells are pluripotent this means they can differentiate into any specialised cells
43
describe where the 2 different types of stem cells are found in animals and explain their function
embryonic stem cells are found in the embryos and can differentiate into the human body. tissue stem cells are found in human tissue and can only differentiate into specialised cells found in the specific tissue.
44
explain where meristems are found and their function.
meristem at the tips of the roots provide a constant supply of news cells allowing roots to grow longer. Meristems at the tips of shoots allow a plant to keep growing taller and spread wider. Meristems between the Xylem and phloem increase the width of a plant.
45
Explain how the patterns of gene expression lead to differences in different cell types
selective gene expression means genes can be switched on or off when they are required, producing protein cells where they are needed.
46
explain what is meant by cellular differentiation
cellular differentiation is the process by which a cell expresses certain genes to produce proteins characteristics for that type of cell.
47
give an account of RNA splicing
In the primary transcript the introns are removed and the exons are spliced together to produce the mature transcript, the axons are expressed and the introns are not expressed, then alternative RNA splicing produces different mature transcripts, this is dependant on the order or combination of axons that are spliced together.
48
explain the structure and functions of different types of RNA.
mRNA is a single strand of nucleotides comprised of ribose sugar, phosphate, and a base, the bases do not contain Thymine but instead Uracil. mRNA takes a copy of DNA code form the nucleus to ribosome.
49
describe the translation of mRNA
tRNA has an anticodon and an amino acid attachment site. tRNA carries a specific amino acid to the ribosome, the anticodons are complementary pairs to the codons on mRNA, on the mRNA there are start codons and stop codons, when amino acids are being joined peptide bonds form between the amino acids.
50
describe the production of mRNA
RNA polymerase unzips and unwinds DNA into 2 strands and breaks the hydrogen bonds, RNA polymerase then adds RNA nucleotides to their complementary base, which produces a primary transcripts this is comprised of exons which are coding regions and introns which are non-coding regions, the introns are removed and the exons remain and are spliced together to form the mature transcript.
51
give an account of protein structure
proteins are made of a chain of amino acids, held together by peptide bonds and are polypeptide folded to form 3-dimensional shapes and are held together by hydrogen bonds and other interactions between amino acids.
52
give an account of how different proteins can be produced from the expression of the same gene
alternative RNA splicing can cause different mature RNA transcriptions produced from the same primary transcript, depending on which axons are retained, different base sequence in the mature transcripts and different amino acids sequences in polypeptide produced.
53
Describe how amino acids are joined to make a protein and the chemical bounds which form to make proteins different shapes
amino acids are linked by peptide bonds to form polypeptides. a polypeptide chain folds to form the 3-dimensional shape of a protein held together by hydrogen bonds and other interactions between individual amino acids.
54
describe how different proteins can be made from the same gene
the sequence of amino acids in the chain determines how the chain will fold up to make the protein.
55
state what is meant by a codon and where it is found, and state what is meant by an anticodon and where it is found.
a codon is a triplet of bases, found in the mRNA. an anticodon is an exposed triplet of bases found on the tRNA.
56
describe the basic process of translation
Translation is the synthesis of a polypeptide following the code within the mature transcript. the ribosome binds to the 5' end of the mature transcript the start codon (AUG). A tRNA carrying the amino acid methionine because attached to the ribosome. The ribosome then moves to the next codon and searches for a tRNA with an anti-codon that matches. A peptide bond forms between the amino acids. The ribosome then moves along to the next codon. The end process is repeated until it reaches a stop codon.
57
describe what occurs during RNA splicing and what is meant by introns and exons.
After the mRNA has been transcribed the introns (non-coding regions) are removed. The remaining exons (coding regions) are spliced together, this produces the mature transcript, which leaves the nucleus and travels to the ribosome.
58
describe the basic process of transcription
transcription is the synthesis of mRNA from a section of DNA. RNA Polymerase binds to the promoter the double helix and breaking hydrogen bonds. RNA Polymerase adds RNA nucleotides onto 3' end, the molecule elongates until it reaches the terminator sequence this produces the primary transcript (mRNA)
59
state the differences between DNA and RNA
DNA is double stranded has deoxyribose sugar and thymine as a base. RNA is single stranded and has uracil as a base.
60
name the 3 types of RNA involved in gene expression and what they are used for.
mRNA - carries a complementary DNA sequence to the ribosome tRNA - carries specific amino acids to the ribosome rRNA - forms the ribosome with proteins which is the site of translation
61
name the 2 stages of gene expression and where they occur in the cell
Transcription happens in the nucleus translation happens in the ribosome
62
Explain what is meant by gene expression
gene expression is the transcription and the translation of DNA sequences
63
define what is meant by a species
a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding
64
explain what is meant by horizontal gene transfer and how it creates faster evolution in prokaryotes
in prokaryotes genetic material can be transferred from one cell to another through horizontal gene transfer horizontal gene transfer is obtaining a gene from a neighbour is much faster than waiting for one to evolve.
65
explain what is meant by disruptive selection.
selection pressure selects extreme versions of a trait at the expense of the intermediate versions, this can result in the population being split into 2 distant groups.
66
explain what is meant by directional selection
selection pressure favours less common versions causing a progressive shift in the mean value
67
explain what is meant by stabilising selection
selection pressure favours less common versions causing a progressive shift in the mean value
68
define what is meant by natural selection
natural selection is non-random which results in the increase in frequency of DNA sequences that increases survival and the non-random reduction in the frequency of deleterious sequence.
69
define what is meant by evolution
evolouion is the gradual change in the characteristic of a population of organisms over successive generations as a result of variation in the population of genomes.
70
describe the stages of speciation
large interbreeding population isolation of populations separate populations mutate randomly natural selection favours mutants over a long period of time natural selection increases frequency of new alleles seperation has occurred species A & B cannot interbreed even if the barrier is removed.
71
name the isolating barrier in allopatric speciation
allopatric - geographical barrier
72
name the isolating barriers in speciation
allopatric sympatric
73
name the isolating barriers in sympatric speciation
behavioural barrier ecological barrier
74
give an account of allopatric and sympatric speciation
in allopatric speciation a geographical barrier prevents gene flow. In sympatric speciation a behavioural and ecological barrier prevents gene flow. Mutations then occur in each sub population. Natural selection then favours the mutated sub population therefore speciation occurs when 2 populations can no longer interbreed to make fertile offspring.
75
one type of selection pressure is stabilising selection. give an account on populations.
stabilising selection favours individuals with a central value in the range of variation. whereas, directional selection favours individuals with characteristics on an extreme end of the range of variations. And disruptive selection values in a range of variations and also acts against the middle of the range.
76
Give an account of the roles of mutation and natural selection
mutations produces a variation within a species. Mutations can be harmful or beneficial. There is a struggle for survival between individuals of the species. Those who are the fittest have a selective advantage of survival. The surviving populations then reproduce and pass on their mutations to the offspring. After a long time a new species forms, and speciation occurs when 2 populations can no longer interbreed to create fertile offspring.
77
give an account of the roles of enzymes in DNA replication and PCR
DNA polymerase adds complementary nucleotides to the deoxyribose 3' end of a DNA strand. Fragments of DNA are joined together by ligase. Heat-tolerant DNA polymerase, replicates the region of DNA.
78
Notes on DNA Replication
DNA unwinds and unzips to form two template strands DNA polymerase needs a primer to start replication DNA polymerase adds complementary nucleotides to the deoxyribose 3' end of a DNA strand resulting in one strand being replicated continuously and the other strand replicated in fragments Fragments of DNA are joined together by ligase.
79
Notes on amplification of DNA
DNA heated to separate strands cooling allows primers to bind to target sequences primers are complementary to specific target sequences at the 2 ends of the region to be amplified heat tolerant DNA polymerase replicates the region of DNA Repeated cycles of heating and cooling amplify this region of DNA
80
Draw and correctly label a nucleotide
phosphate (5') Deoxyribose (3') base
81
name the bases and describe the base pairing rule
adenine = thymine cytosine = guanine
82
name the bonds between the bases
hydrogen bonds
83
Explain what is meant by anti-parallel
The 2 chains of nucleotides form in different directions as one side goes from 5' to 3' and the other side goes from 3' to 5'.
84
state the difference between a prokaryote and a Eukaryote.
prokaryotes - bacterial cells, no nucleus, circular chromosomes, plasmids, yeast have plasmids Eukaryotes - animal, plant, fungi cells, with nucleus, linear chromosomes, DNA tightly coiled wrapped around histone proteins, circular mitochondria and chloroplast DNA
85
give an example of a prokaryote and a eukaryotes
prokaryotes are bacterial cells Eukaryotes are animal, plant, and fungi cells
86
describe how DNA is organised in a prokaryotic cell
prokaryotes usually have single circular double stranded chromosomes and some have a plasmid which carries non-essential genes.
87
describe how DNA is organised in a eukaryotic cell
eukaryotes are organisms with a nucleus containing several linear chromosomes, they also have extra DNA in the mitochondria and the chloroplast. The DNA is tightly coiled and wrapped around histones proteins
88
name the protein used to package DNA
histone proteins
89
organisation of DNA in eukaryotic and prokaryotic cells
prokaryotes have circular chromosomes and plasmids, yeast also have plasmids. Eukaryotes have linear chromosomes found in the nucleus, on top of that eukaryotes have circular DNA in the chloroplast and mitochondria, eukaryotic DNA is tightly coiled around histones proteins.
90
Give an account of the structure of a DNA molecule
DNA is a double helix, each strand is composed of nucleotides. A nucleotide is made up of a phosphate, deoxyribose sugar, and a base. All the sugar-phosphates make up the backbone of DNA. The complementary base pairing means adenine goes with thymine and cytosine goes with guanine. The 2 strands of DNA are antiparallel.
91
describe the function of DNA and give an account of the structure of a DNA molecule
DNA function is to carry the genetic code, in the base sequence DNA's structure is a double helix of anti-parallel strands of nucleotides joined by complementary base pairing. The nucleotides are made up of deoxyribose sugar, a phosphate and a base, the sugar-phosphates are the backbone of DNA.

Biology (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions