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A-level Biology > CLASSIFICATION + DIVERSITY > Flashcards

CLASSIFICATION + DIVERSITY Flashcards

TOPIC 4

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1
Q

GENE

A

section of DNA that contains code for making polypeptide + functional RNA

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2
Q

LOCUS

A

location of particular gene on chromosome

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3
Q

ALLELE

A

location of particular gene on chromosome

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4
Q

CHROMOSOME

A

threadlike structure composed of tightly coiled DNA + wrapped around histones

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5
Q

HOMOGLOUS CHROMOSOMES

A

pair of chromosomes that have same genes therefore- same size

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6
Q

PROKARYOTIC DNA

A

Shorter
Circular
Not associated w/histones
No nucleus
May have plasmids
Only exons

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7
Q

EUKARYOTIC DNA

A

Longer
Linear
Associated w/ histones
Contains nucleus
No plasmids
Have introns + exons

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8
Q

CODON

A

3 bases on mRNA- code for amino acid

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9
Q

START CODON

A

3 bases at start of mRNA sequence which help initiate translation

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10
Q

STOP CODON

A

3 bases at end of every gene that don’t code for amino acid- ribosomes to detach + therefore stops translation

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11
Q

UNIVERSAL

A

code universal for all living things

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12
Q

GENETIC CODE

A

amino acid is coded for by 3 DNA bases which- described as “triplet code”

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13
Q

ADVANTAGE OF THE CODE BEING UNIVERSAL

A

genetic engineering is possible human gene can be inserted into another organism
e.g human gene for insulin inserted to bacteria to make insulin

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14
Q

NON-OVERLAPPING

A

each triplet is read separately

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15
Q

ADVANTAGE OF THE CODE BEING NON-OVERLAPPING

A

if point mutation occurs, it will only affect one codon and therefore one amino acid

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16
Q

DEGENRATE

A

each amino acid is coded for by
more than one triplet of bases

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17
Q

ADVANTAGE OF THE CODE BEING DEGENERATE

A

if substitution mutation occurs new triplet of bases may still code for same amino acid
therefore mutation will have no impact on final protein produced

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18
Q

MUTATION

A

change in DNA can be gene or chromosome mutation

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19
Q

INTRON

A

non-coding sequence of DNA

20
Q

EXON

A

sequences in gene that code for amino acid sequences

21
Q

MRNA

A

.Single stranded
.Linear chain
.Longer chain/ has more nucleotides
.Corresponds to genetic sequence of gene
.Unpaired bases

22
Q

MRNA FUNCTION

A

copy of gene from DNA created in nucleus, and it then leaves nucleus to carry copy of genetic code of one gene to ribosome in cytoplasm

23
Q

TRNA

A

.Single stranded folded into a clover shape
.Hydrogen bonds
.Anticodon
.Amino acid attachment site
.All similar lengths

24
Q

TRNA FUNCTION

A

single-stranded, folded to create cloverleaf shape held in place by hydrogen bonds
has an anticodon and amino acid binding site

25
Q

GENEOME

A

complete set of genes in cell

26
Q

PROTEOME

A

full range of proteins that cell is able to produce

27
Q

POLYPEPTIDE SYNTHESIS

A

.sequence of nucleotides on gene on DNA acts as template
.complimentary copy is transcribed onto mRNA in nucleus
.At ribosomes mRNA acts as template that is translated to chain of amino acids using complementary tRNA which carry specific amino acids which are linked together

28
Q

TRANSCRIPTION FROM DNA TO MRNA

A

1.H bonds between complementary base pairs of gene to be transcribed are broken DNA nucleotide bases are now exposed

2.One strand acts as template to make an mRNA copy

3.Free RNA nucleotides alongside their complementary base pair on template strand of DNA-Uracil replaces thymine on mRNA

4.RNA polymerase joins adjacent nucleotides together w/phosphodiester bond

5.RNA Polymerase continues until it reaches stop signal and then it detaches + introns are removed

29
Q

PRE-MRNA + SPLICING

A

.eukaryotic cells, mRNA produced during transcription contains both introns and exons-this is pre-mRNA
.introns need to be removed because they don’t contain any genetic information that can be translated into an amino acid sequence
.introns are “spliced” out of mRNA sequence by an enzyme
.produces strand of mRNA that contains only exons - coding regions- known as mature mRNA

30
Q

TRANSLATION OF MRNA TO FORM POLYPEPTIDE

A

1.mRNA attaches to a ribosome

2.tRNA anticodons bind to complementary codons on mRNA

3.tRNA brings a specific amino acid

4.two tRNA can bind simultaneously

5.Adjacent amino acids undergo condensation reaction and form peptide bond-using ATP

6.First tRNA detaches and ribosome moves to next codon

7.This continues, forming polypeptide until STOP codon is reached and ribosome detaches

31
Q

HAPLOID

A

one copy of each chromosome in cell

32
Q

DIPLOID

A

two copies of each chromosome in cell

33
Q

MEOSIS

A

Meiosis I is reduction division separation of homologous pair of chromosomes:
.Homologous pairs are separated
.Variation is introduced

Meiosis II is similar to mitosis w/separation of sister chromatids
Four haploid cells are produced, each w/ half diploid number of chromosomes

34
Q

CROSSING OVER

A

occurs in prophase I w/ formation of chiasmata

1.Homologous pairs of chromosomes associate and form bivalent
2.Chiasmata forms
3.Equal lengths of non-sister chromatids or alleles are exchanged
4.Producing new combinations of alleles

35
Q

IDEPENDANT SEGREGATION

A

1.Metaphase 1, homologous pairs line up either side of equator
2.completely random which side of equator maternal and paternal chromosomes line up on
3.When separated, one of each pair ends up in daughter cell
4.‘shuffling’ leads to different combinations of maternal and paternal chromosomes in daughter cells

36
Q

OTHER SOURCES OF VARIATION

A

.Fertilisation: random mating w/random gametes –results in random fusion of gametes and produces new allele combinations/new maternal and paternal chromosome combinations
.mutations may occur

37
Q

INSERTION

A

extra base is added during DNA replication results in frame shift – all codons after mutation are affected

37
Q

MITOSIS VS MEOISIS

A

Same number of chromosomes VS Half number of chromosomes
Genetically identical VS Genetically different
Two cells VS Four cells

38
Q

DELETION

A

One base is left out during DNA replication results in frame shift – all codons after mutation are affected

38
Q

SUBSITUTION

A

One base is changed for another during DNA replication-Only codon w/mutation is affected

39
Q

CHANGE IN CODON RESULTS CHANGE IN PROTEIN

A

.amino acid sequence changes
.hydrogen/ionic/disulphide bonds between R groups changes
.tertiary structure changes

40
Q
A
41
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42
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43
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44
Q
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A-level Biology (9 decks)

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