Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AQA A Level Biology > 3.4 Genetic information, variation and relationships between organisms > Flashcards

3.4 Genetic information, variation and relationships between organisms Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Describe Eukaryotic DNA

A

Long
Linear
Associated w/ Histones (proteins)
Coiled

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

Describe Prokaryotic DNA

A

Short
Circular
Not Associated w/ Histones (proteins)

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

Describe DNA in mitochondria and chloroplasts

A

Similar to prokaryotic DNA
Short
Circular
Not associated with proteins

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

What is a gene?

A

Section of DNA that codes for the amino acid sequence of a polypeptide and functional RNA (tRNA and rRNA)

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

What is a locus/loci?

A

Specific linear position of a gene on a certain chromosome

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

What is a histone?

A

Proteins which together with DNA

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

What is the nature of the genetic code?

A

Triplet (sequence of three DNA bases) for specific amino acid
Universal
Non-overlapping
Degenerate

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

What is an exon?

A

Portion(s) of DNA within a gene that codes for proteins

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

What is an Intron?

A

Portion(s) of DNA within a gene that does not code for proteins

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

What is an Allele?

A

Alternative form of a gene with different base sequences (and therefore codes)

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

Define genome

A

The complete set of genes in a cell

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

Define proteome

A

The full range of proteins that a cell/genome is able to produce

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

Define Homologous Pair of chromosomes

A

Pair of chromosomes with the same gene but different alleles

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

Describe the structure of messenger RNA (mRNA)

A 
Single stranded 
Straight chain helix 
Made during transcription 
Codon
Pentose sugar = ribose 
A,C,G,U = bases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the structure of Transfer RNA (tRNA)

A 
Single polynucleotide chain 
Ribose 
Three leafed Clover-shaped molecule 
Amino acid binding site 
Anticodon
Held by hydrogen bonds
short
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are similarities between trna and mrna?

A

Both single polynucleotide strands

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

What are the differences between tRNA and mRNA?

A
  • mRNA single helix / straight, whereas tRNA folded into clover shape
  • mRNA is a longer, variable length, whereas tRNA is shorter
  • mRNA contains no paired bases or hydrogen bonds, whereas tRNA has some paired bases and hydrogen bonds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the process of Transcription

A

Occurs in the nucleus
DNA helix unwound by DNA Helicase = Hydrogen bonds broken
Formation of template strand
RNA nucleotides align next to exposed nucleotide bases on template strand
RNA polymerase joins adjacent nucleotides through condensation reaction
Forms phosphodiester bonds
When reached to stop codon pre-mRNA detached from DNA
Splice the pre-mRNA (removal on introns)
Creation of mMRNA

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

What is meant by post transcriptional modification?

A

Splicing of Pre-mRNA

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

Describe the process of Translation

A

mRNA attaches to ribosomes
tRNAs codon binds to mRNA codon
Begins with start codon
tRNA will attract specific amino acids with two trna molecules at a time
Two amino acids joined by condensation reaction using ATP
Formation of peptide bond
tRNA attaches and ribosome moves along mRNA to next codon
Continues until stop codon

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

What is the role of ATP in translation?

A

Releases energy through its hydrolysis

The bond between amino acid and tRNA molecules → Peptide bond

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

What is the role of tRNA?

A

Attaches and transports specific amino acid (relation to anticodon)

Two trnas bring amino acid together for peptide bond

Degenerate genetic code

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

What is the role of the ribosomes in translation?

A

Attaches to mRNA and houses tRNA allowing codon-anticodon complementary base pairing

Factory for protein synthesis

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

What is a gene mutation?

A

A change in the base sequence of DNA (chromosomes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the types of mutation?

A

Substitution

Deletion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How can a mutation lead to the formation of a nonfunctional protein

A
  • Change in base / triplet sequence of DNA / gene
  • Changes sequence of codons on mRNA
  • Changes sequence of amino acids in the primary structure of the polypeptide
  • Changes position of hydrogen / ionic / disulphide bonds in tertiary structure of protein
  • Changes tertiary structure / shape of the protein (and active site if enzyme)
  • (if enzyme) substrate can’t bind to active site and form an enzyme-substrate complex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Explain Base deletion

A

One base is removed from DNA sequence
Alters the codon sequence from point of mutation known as frameshift
Changes sequence of codons on MRNA
Change in amino acid primary structure of polypeptide
Changes bonds in Tertiary structure of protein
Shape of protein changes due to different amino acids being codes for

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Explain ‘base substitution’

A

The nucleotide in DNA is replaced with another nucleotide = Causes change in one triplet

Changes one mRNA codon and one amino acid codon
Sequence of amino acids in primary structure changes
OR
2. Due to the degenerate nature of the genetic code, the new triplet may still code for the same amino acid (primary structure remains the same.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the role of mutagenic agents?

A

Increase the rate of gene mutation

30
Q

What are mutagenic agents?

A

Environmental factors that increase the mutation rate of cells

31
Q

Give an example of a mutagenic agent?

A

UV, X-rays(ionising radiation) or toxic chemicals

32
Q

Describe Process of Meiosis 1

A

Condensed Dna replicates so there are two copies of each chromosome → sister chromatids held by centromere

M1
Prophase I = Bivalents and spindle fibre formation. Crossing over occurs increasing genetic variation. Nuclear envelope breaks down
Metaphase I = Chromosomes line up in the equator of the cell with spindle fibres attached to centromeres. Independent assortment
Anaphase I - Spindle fibres pull chromosomes apart to opposite poles of the cell → independent segregation
Telophase I - Chromosomes uncoil, spindle fibres break down, nuclear envelope forms around → two new Haploid daughter cells

33
Q

Describe the process of Meiosis II

A

Prophase II
Nuclear envelope breaks down
Chromosomes condense
Spindle fibres form

Metaphase II
Chromosomes line up along the equator of the spindle

Anaphase II
Centromeres divide and chromatids are pulled to opposite ends
(Four groups of chromosomes that have ½ number than original parent cell)

Telophase II
Nuclear membranes form around each group of chromosomes

Cytokinesis
Cytoplasm divides as new cell surface membranes are formed → four haploid cells that are genetically varied

34
Q

How does meiosis create genetic variation

A

Crossing over between homologous chromosomes → alleles exchanged between chromosomes
New combinations of maternal and paternal alleles

Independent segregation → random alignment of homologous pair at equator = random selection of chromosome to each daughter cell
- Creates different combinations of maternal and paternal chromosomes and alleles in daughter cells

Random fertillisation when two gametes fuse to form a zygote

35
Q

What is the importance of meiosis?

A
  • Two divisions – creates haploid gametes (half number of chromosomes)
  • Diploid number restored at fertilisation
  • Maintains chromosome number from one generation to the next
  • Independent segregation and crossing over creates genetic variation
36
Q

Describe the non-disjunction mutation that occurs in meiosis

A

Homologous chromosomes fail to separate during M1 (OR sister chromatids fail to separate in M2) during anaphase

One gamete has extra copy of a chromosome and the other has none

Zygote will have one fewer (dies) or one extra (survives) chromosome

Arises spontaneously

Causes genetic diseases exp. Down syndrome in humans - extra copy of chromosome 21

37
Q

Explain the different outcomes of mitosis and meiosis

A

Mitosis produces diploid cells whereas meiosis produces haploid cells

There are two divisions in Meiosis whereas there is only one division in mitosis

Daughter cells are genetically identical in Mitosis but in Meiosis, the daughter cells are genetically varied

Crossing over and Independent segregation only in Meiosis

Mitosis produces two daughter cell but Meiosis produces 4 daughter cells

38
Q

What is genetic diversity?

A

Number of different alleles of a gene in a population

39
Q

Explain the principles of natural selection in the evolution of population

A
  1. Random DNA mutations cause the variation of alleles in a population
  2. Selection pressure / change in environment
  3. Those with advantageous allele have increased chance of survival and reproduction – differential survival/reproductive success
  4. Those surviving pass advantageous allele to offspring
  5. Frequency of advantageous allele and (named) characteristic increases in the population
  6. Over many generations / long period of time
40
Q

In terms of alleles, what is evolution?

A

Change in allele frequency over time

41
Q

Describe directional selection

A

Occurs when there is a change in the environment due to new selection pressure/allele in population

Frequency of allele in population increases

Mean variation within population will shift towards one characteristic (phenotype)

one extreme phenotype is more likely to survive and produce

42
Q

Describe stabilising selection

A

Restricts the variation within a characteristic around the mean
Selection pressure acts either side of the mean
Both extremes of phenotypes less likely to survive and reproduce
Mean phenotype remains the same

43
Q

Describe disruptive selection

A

Maintains frequencies of two different sets of alleles - both extremes

Causes continues existence of two or more distinct phenotypes in species
Occurs in environment that show variation
Individuals with intermediate phenotypes or alleles are selected against

44
Q

Name the three categories of adaptation Natural selection can provide

A

Anatomical
Physiological
Behavioural

45
Q

Define ‘species’

A

A group of organisms (that have a common ancestry + share the same gene) that are capable of breeding together to produce fertile offspring

46
Q

Why may offspring from 2 different species mating be infertile?

A

They will have an odd number of chromosomes so cant perform meiosis to produce (haploid) sex cells (gametes)

47
Q

Explain the necessity of courtship behaviour to successful mating

A

Allows recognition of members of the same species to produce fertile offspring through successful mating

48
Q

Give at least 2 roles of courtship in species recognition?

A 
Indication of sexual maturity 
Attraction of opposite sex 
Stimulate release of gametes 
Establishes a pair bond to raise children 
Synchronise mating
49
Q

What is the phylogenetic classification system?

A

Process of classifying organisms based upon evolutionary origins and relationships

50
Q

What is a hierarchy?

A

Where Smaller groups are placed within larger groups with no overlap between each group

51
Q

What is each group in the phylogenetic classification system called?

A

Group = taxon

52
Q

Give the names of the taxonomic ranks

A
  • Domain (Delicous )
  • Kingdom (King)
  • Phylum (Prawns)
  • Class (Curry)
  • Order (or)
  • Family (Fat)
  • Genus (Greasy)
  • Species (Sausages)
53
Q

What is the advantage of binomial naming of specious (using genus and species)

A

Universal = no confusion as many organisms have more than one common name

54
Q

What advances in immunology and genome sequencing help to clarify evolutionary relationships between organisms?

A

Genome sequencing
Compare the order of base sequence of the whole genome of different species
Higher match =more closely related

Immunology
DNA→mRNA→ sequence of amino acids in polypeptide
Tertiary structure of protein tells about sequence
If same antibody binds to a specific antigen then closely related

55
Q

Define Biodiversity

A

The variety of living organisms in an area

56
Q

What are the three components of Biodiversity

A

Species diversity = the number of different species and the number of individuals of each species within a community

Genetic diversity = variety of genes/alleles in the population of species

Ecosystem diversity = range of habitats from a small local community to the whole earth

57
Q

What is species richness?

A

The measure of the number of different species in a community

58
Q

What is the index of diversity?

A

The formula used to quantify the biodiversity of a habitat

59
Q

What is species evenness?

A

Comparison of size of population of different species within a particular area

60
Q

What is the lowest possible of Index of Diversity?

A

1

61
Q

What is the impact of Agriculture on Biodiversity

A

Removal of woodland and hedgerows

Monoculture (causes one desirable species )

Use of pesticides, herbicides and inorganic fertilisers

Increasing competition → Crops better competitors e.g light/nutrients

62
Q

What is conservation?

A

Sustainable management of earth’s natural resources that maximise preservation

63
Q

What is variation?

A

Differences between individuals, within a species (intraspecific) or between different species (interspecific)

64
Q

State the features of continuous variation

A

No distinct categories
Quantitative
Strongly influenced by the environment

65
Q

How can we compare genetic diversity?

A

Frequency of measurable observable characteristics
Bases sequence of DNA
Base sequence of mRNA
The amino acid sequence of the proteins encoded by DNA and mRNA

66
Q

State the features of discontinuous variation

A

Distinct, discrete categories
Qualitative
Unaffected by environment

67
Q

How and why has gene technology caused a change in the methods of investigating
genetic diversity?

A

Before genetic diversity was measured by looking at frequency of observable characteristics:
Limitations:
many observable features coded for by more than one gene → different to distinguish
Could be modified by environment so differences may be result of environment conditions rather than different alleles

Gene technology ☑ - Directly obtain DNA sequences = more accurate:

Different alleles of same gene have different base sequences → can compare base sequences of same gene in different organisms→ find out number of that gene in a population

Can produce slightly different amino acids sequences which can be compared

68
Q

How would you take a representative sample and why?

A

Random sample
Eliminates bias

Exp. number generator for coordinates for quadrats

69
Q

Why is using a large sample size beneficial when investigating variation within a species?

A

Minimise effects of chance

Anomalies have less influence and can be identified

70
Q

What does it mean if the standard deviation of two values overlap?

A

Any difference between the two may be due to chance, there is no significant difference (consider they are technically similar values)

AQA A Level Biology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions