Brainscape's Knowledge GenomeTM

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


See full index

AQA Biology A-level > Genetic information and variation > Flashcards

Genetic information and variation Flashcards

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

DNA in prokaryotic cell is

A

short, circular and not associated with histone proteins

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

DNA in eukaryotic nucleus is

A

long, linear and associated with histone proteins

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

DNA in chloroplast / mitochondrion is

A

short, circular and not associated with histone proteins

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

In eukaryotic nucleus, a DNA molecule, made up of 2 polynucleotide strands, is

A

twisted into a double helix around associated histones (proteins)

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

gene

A

section of DNA located at a fixed location on a particular chromosome (locus)

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

the sequence of bases (adenine, thymine, cytosine, guanine) of a gene carries the oded genetic information that determines:

A
  • a.a. sequence of a polypeptide during protein synthesis
  • a functional RNA molecule that isn’t translated into a protein but has a biological unction (including ribosomal RNA (rRNA) and transfer RNA (tRNA)).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

genome

A

a complete set of genes in a cell

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

proteome

A

the full range of proteins that a cell is able to produce

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

the genetic code is carried as a sequence of 3 DNA bases, called a

A

triplet or codon

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

the genetic code is:

A
  • universal
  • non-overlapping
  • degenerate (more than one triplet code for most amino acids)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

mRNA and tRNA share some structural similarities:

A
  • single polynucleotide chain
  • pentose sugar, ribose and the bases adenine, uracil, guanine and cytosine.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

structure of mRNA

A

longer cain than tRNA, single stranded helix molecule, chemically unstable; only present when required for protein synthesis

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

structure of tRNA

A

short chain, clover-leaf shaped; has a.a. attachment site on ‘stalk’ and anticodon mRNA binding site on lower lower, chemically stable.

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

protein synthesis is the mechanism in cells whereby:

A
  1. a DNA template is transcribed into mRNA in the nucleus
  2. the mRNA base sequence is then translated into an a.a. sequence in association with tRNA o ribosomes in the cytoplasm.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

transcription

A

the production of mRNA using DNA

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

the process of transcription:

A
  1. DNA helicase breaks hydrogen bonds between bases, causing DNA to unzip and expose bases
  2. RNA polymerase moves along the DNA template strand and attaches free nucleotides to their complementary bases on the DNA.
  3. RNA polymerase makes short strands of pre-mRNA until it comes to a terminator sequence
  4. sections of pre-mRNA are spliced together to remove intron sequences and join exon sequences to form mRNA.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

splicing

A

introns (non-coding regions of genes) are removed from the pre-mRNA molecule, and the exons (coding regions) are joined together to form the mature mRNA.

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

Translation

A

production of polypeptides from the sequence of codons carried by mRNA.

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

process of translation

A
  1. mRNA moves from nucleus through a nuclear pore to the cytoplasm and the start codon (AUG) attaches to a ribosome.
  2. tRNA (carrying specific a.a, methionine) with complementary anticodon (UAC) moves to the ribosome and pairs with the first mRNA codon
  3. ribosome moves along the mRNA to the next codon and again pairs up with a complementary tRNA to bring the 2 a.a. carrying tRNAs together.
  4. energy released from ATP is used to form a peptide bond between the a.a.
  5. ribosome moves to the third mRNA codon, releasing the first tRNA and pairing up with a third
  6. when the ribosome reaches a stop codon, the polypeptide is complete and the mRNA and tRNAs are released from the ribosome.
  7. the tRNA molecules released from the ribosome can then be reused.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

chromosome

A

1 molecule of DNA with both polynucleotide strands twisted together to form a double helix wrapped around histone proteins.

21
Q

mutation

A

spontaneous change in the base sequence of chromosomes

22
Q

during DNA replication there can be:

A

base insertion or deletion -> frameshift
base substitution

23
Q

not all mutations cause a change in sequence of encoded amino acids because

A

the genetic code is degenerate

24
Q

this is because all base triplet combinations only code for

A

20 amino acids, which allows for some mutations to occur without affecting the amino acids produced.

25
Q

mutagenic agents

A
  • can be chemicals or radiation
  • can increase the rate of gene mutation.
26
Q

examples of mutagenic agents

A
  • ionising radiation (UV, X-rays)
  • some viruses and microorganisms (HPV)
  • unhealthy diet (alcohol, high fat)
  • mutagenic chemicals (asbestos, tobacco tar)
27
Q

crossing over

A

homologous chromosomes cross over, increasing genetic variation amongst daughter cells.

28
Q

mitosis

A

forms somatic cells
diploid to diploid / haploid to haploid
2 genetically identical daughter cells produced
no independent segregation
no crossing over

29
Q

meiosis

A

forms gametes
diploid to haploid
4 genetically different daughter cells produced
homologous chromosomes randomly segregated during meiosis I
non sister chromatids in prophase I can cross over and exchange genetic variation.

30
Q

natural selection can result in different types of adaptations in species:

A
  1. anatomical adaptations
  2. physiological adaptations
  3. behavioural adaptations
31
Q

directional selection

A
  • if a new selection pressure or allele appears in a population, the allele frequency in the population may change.
  • individuals with advantageous characteristics will survive and reproduce, passing alleles onto offspring.
  • causes frequency of these alleles to increase, and mean variations within population shifts towards one characteristic.
32
Q

genetic diversity

A

measure of the number of different alleles in a population
- enables natural selection to happen.

33
Q

Natural selection

A
  1. in a population, there is genetic variation, which is increased by random mutations producing new alleles
  2. most mutations are neutral, some are detrimental, but occasionally a new allele may be advantageous to an individual in a specific environment. This increases the chances of reproductive success
  3. the advantageous allele will be inherited by more individuals in the next generation
  4. the advantageous allele will increase in frequency in the population in future generations.
34
Q

stabilising selection

A

restricts the variation within a characteristic around the mean (e.g. birth weight)

35
Q

taxonomy

A

the science of naming, defining and classifying groups of organisms based on their shared characteristics.

36
Q

phylogenetic classification

A
  • Arranges species into groups based on their evolutionary origins and relationships.
  • Uses a hierarchy where smaller groups are placed within larger groups, with no overlap between groups.
  • Each group is called a taxon.
37
Q

One system has the hierarchy:

A

Domain, kingdom, Phylum, Class, Order, Family, Genus, Species

38
Q

species

A

a group of similar organisms that can breed together to produce fertile offspring

39
Q

binomial (scientific name)

A

genus and species. This name can be identified universally.

40
Q

courtship

A

A mechanism of species recognition and is necessary to ensure successful mating.

41
Q

Courtship tables individuals of a species to:

A
  • recognise members of own species
  • identify a mate capable of breeding
  • synchronise mating
  • form a pair bond.
42
Q

biodiversity

A

the variety of organisms living within a particular area or habitat.
- it includes ecosystems, species, and the number of different alleles.

43
Q

Habitat

A

the place where individuals of a species live, with a specific set of biotic and abiotic factors.

44
Q

Index of diversity

A

d = N (N-1) / the sum of n(n-1)

45
Q

Modern farming practices reduce biodiversity:

A
  • ponds, hedgerows and woodland are removed
  • marshes and wetlands are drained
  • non-selective pesticides kill non-target species

there must be a balance between farming and conservation, to help increase biodiversity but keep yields high.

46
Q

analysing index of diversity

A
  • high value indicated that a habitat is diverse with many species. The habitat will be stable and resilient to changes within the area.
  • a low value indicates that the habitat has low diversity and is dominated by a few species. These habitats can be affected by small changes such as droughts and disease.
47
Q

Genetic diversity within (intraspecific variation), or between (interspecific variation), species can be made by comparing:

A
  • the similarities of measurable or observable characteristics (traditional approach)
  • the base sequence of DNA
  • the base sequence of mRNA
  • the amino acid sequence of the proteins encoded by DNA and mRNA.
48
Q

quantitative investigations of variation within a species involve:

A
  • collecting data from random samples from a single population
  • calculating a mean value of the collected data and the standard deviation of that mean
  • interpreting mean values and their standard deviations.

AQA Biology A-level (8 decks)

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