Brainscape's Knowledge GenomeTM

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


See full index

AQA AS Biology > genetics, biodiversity and classification > Flashcards

genetics, biodiversity and classification Flashcards

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

prokaryotic DNA is…

A
  • short
  • circular
  • not associated with proteins.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

eukaryotic DNA is…

A
  • very long
  • linear
  • associated with proteins called histones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Together a DNA molecule and its associated proteins form a…

A

chromosome

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

The mitochondria and chloroplasts of eukaryotic cells also contain…

A

DNA

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

The mitochondria and chloroplasts of eukaryotic cells contain DNA which is…

A

like the DNA of prokaryotes
- short
- circular
- not associated with protein.

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

a gene is…

A

a base sequence of DNA that codes for:

  • the amino acid sequence of a polypeptide
  • a functional RNA (including ribosomal RNA and tRNAs).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

A gene occupies a fixed position, called…

A

a locus, on a particular DNA molecule.

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

what’s a triplet?

A

A sequence of three DNA bases

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

what does a triplet do?

A

it codes for a specific amino acid

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

universal meaning

A

all living organisms on Earth use the same genetic code

This provides indirect evidence for evolution.

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

non overlapping meaning…

A

each codon codes only for its particular amino acid

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

degenerate meaning…

A

more than one triplet codes for the same amino acids

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

exons code for…

A

amino acid sequences

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

introns are…

A

non-coding sequences

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

the genome is…

A

complete set of genes in a cell

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

the proteome is…

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
18
Q

The structure of molecules of messenger RNA (mRNA)

A
  • mRNA is single stranded
  • bases U, A, C, and G
  • Bases are arranged in codons
  • the nucleotides that form mRNA are made up of a base, a phosphate group and pentose sugar called ribose
  • mRNA has a sugar-phosphate backbone
  • Each of the nucleotides in mRNA are attached through phosphodiester bonds between the phosphate and ribose groups. This forms a sugar-phosphate backbone.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The structure of molecules of transfer RNA (tRNA)

A
  • tRNA is single stranded
  • bases U, A, C, and G
  • tRNA is a cloverleaf shape
  • tRNA has two attachment sites. At one end of tRNA, there is an attachment site for amino acids. At the opposite end of tRNA, there is an attachment site for anti-codons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are the 2 stages of protein synthesis?

A

1- transcription
2- translation

21
Q

transcription steps…

A
  • RNA polymerase binds to the beginning of a gene
  • RNA polymerase separates the DNA strands, producing a single DNA template for transcription.
  • As RNA polymerase moves along one of the DNA strands (the template strand), it adds complementary RNA nucleotides and connects them through the formation of phosphodiester bonds.
  • Eventually RNA polymerase will reach a codon which does not code for an amino acid but tells the enzyme to stop transcribing (these are called stop codons)
  • A molecule of messenger RNA (mRNA) has been formed which will leave the nucleus and enter the cytoplasm.
22
Q

In prokaryotes, transcription results directly in the production of…

A

mRNA from DNA

23
Q

In eukaryotes, transcription results in the production of…

A

pre-mRNA, this is then spliced to form mRNA

24
Q

Translation is…

A

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

25
Q

translation steps

A
  • Once in the cytoplasm, the messenger RNA finds its way to structures called ribosomes, which are basically protein-building machines.
  • The ribosome attaches itself to the RNA and slides along it.
  • The ribosome ‘reads’ the mRNA in a series of three bases (such as AUG, CCA, GCU) called codons.
  • Each codon corresponds to a particular amino acid.
  • As the ribosome reads the codons, a transfer RNA (tRNA) molecule which has a complementary anticodon carries an amino acid to the ribosome.
  • Once the ribosome has read through the length of the mRNA, a series of different amino acids will have been dropped off by several tRNA molecules.
  • Peptide bonds form between the amino acids to form a protein
26
Q

gene mutations are…

A

a change in the base sequence of chromosomes
- They can arise spontaneously during DNA replication and include base deletion and base substitution

27
Q

why does substitution not always result in a change to the amino acid sequence?

A
  • Due to the degenerate nature of the genetic code.
    different codons can code for the same amino acid
28
Q

what do mutagenic agents do?

A

Mutagenic agents can increase the rate of gene mutation

29
Q

example of mutagenic agents…

A
  • tobacco products
  • radioactive substances
  • x-rays
  • ultraviolet radiation
  • a wide variety of chemicals
30
Q

how can mutations in the number of chromosomes arise?

A

chromosome non-disjunction

31
Q

what is chromosome non-disjunction?

A

Nondisjunction means that a pair of homologous chromosomes has failed to separate or segregate at anaphase so that both chromosomes of the pair pass to the same daughter cell.

32
Q

Meiosis produces…

A

daughter cells that are genetically DIFFERENT from each other

33
Q

meiosis stages?

A

meiosis 1
meiosis 2

34
Q

what happens during meiosis 1?

A
  1. Homologous chromosomes pair to form bivalents.
  2. Crossing over (exchange of sections of genetic material) occurs at chiasmata.
  3. Cell divides into two. Homologous chromosomes separate randomly.
    Each cell contains either maternal or paternal copy.
35
Q

what happens during meiosis 2?

A
  1. Independent segregation of sister chromatids.
  2. Each cell divides again, producing 4 haploid cells.
36
Q

how does meiosis produce genetic variation?

A
  • crossing over during meiosis 1
  • independent assortment of homologous chromosomes & sister chromatids

resulting in new combinations of alleles.

37
Q

crossing over…

A
  • two homologous chromosomes come together and align, and then recombine and swap parts with each other.
  • Overall, crossing over results in the creation of new alleles and ensures that offspring are not genetically identical to their parents.
38
Q

Independent Assortment…

A
  • In meiosis II, each pair of homologous chromosomes is split up.
  • When the pair splits up, each daughter cell will receive one chromosome.
  • The allocation of this is completely random – hence we call it independent assortment.
39
Q

genetic diversity is…

A

the number of different alleles of genes in a population.

40
Q

Genetic diversity is a factor enabling…

A

natural selection to occur

41
Q

Random mutation can result in…

A

new alleles of a gene

42
Q

Many mutations are harmful but, in certain environments, the new allele of a gene might benefit its possessor, leading to…

A

increased reproductive success

43
Q

The principles of natural selection in the evolution of populations…

A
  • Random mutation can result in new alleles of a gene.
  • Many mutations are harmful but, in certain environments, the new allele of a gene might benefit its possessor, leading to increased reproductive success.
  • The advantageous allele is inherited by members of the next generation.
  • As a result, over many generations, the new allele increases in frequency in the population
44
Q

Natural selection results in…

A
  • species that are better adapted to their environment

These adaptations may be anatomical, physiological or behavioural

45
Q

Two organisms belong to the same species if…

A

they are able to produce fertile offspring

46
Q

Courtship behaviour is a necessary precursor to…

A

successful mating

47
Q

A phylogenetic classification system attempts to arrange species into groups based on…

A
  • their evolutionary origins and relationships
  • It uses a hierarchy in which smaller groups are placed within larger groups, with no overlap between groups.
    Each group is called a taxon
48
Q

dark king prawn curry or fat greasy sausages

A

domain, kingdom, phylum, class, order, family, genus and species

49
Q

Species richness is a measure of…

A

the number of different species in a community

AQA AS Biology (6 decks)

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