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tpoic 4 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Gene

A

a section of DNA that contains a code for making a polypeptide and functional RNA

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2
Q

Locus

A

the location of a particular gene on a chromosome

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3
Q

Allele

A

a different version of the same gene

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4
Q

Chromosome

A

threadlike structure
composed of tightly coiled DNA wrapped around histones (if it is a eukaryotic cell)

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5
Q

Homologous chromosome

A

a pair of chromosomes that
have the same genes
therefore, they are the same size

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6
Q

Eukaryotic DNA

A

DNA is stored as chromosomes inside the nucleus
linear chromosomes
DNA is tightly coiled and wrapped around proteins called histones

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7
Q

Prokaryotic DNA

A

DNA molecules are shorter and circular
DNA is not wound around histones. Instead, it supercoils to fit in the cell

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8
Q

Codon

A

3 bases on mRNA that code for an amino acid

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9
Q

Start codon

A

3 bases at the start of an mRNA sequence which help to initiate translation

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10
Q

Stop codon

A

3 bases at the end of every gene that do not code for an amino acid
this causes ribosomes to detach
and therefore stops translation

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11
Q

Genetic code

A

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

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12
Q

What is meant by ‘the genetic code is degenerate?

A

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

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13
Q

What is the advantage of the genetic code being degenerate?

A

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

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14
Q

What is the advantage of the genetic code being universal?

A

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

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15
Q

What is the advantage of the genetic code being non- overlapping?

A

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

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16
Q

Triplet code

A

an amino acid is coded for by 3 bases

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17
Q

Mutation

A

a change in the DNA
can be a gene or chromosome mutation

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18
Q

What is meant by ‘the genetic code is universal?

A

the same triplet of bases codes for the same amino acid in all organisms

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19
Q

What is meant by ‘the genetic code is non-overlapping?

A

each base in a gene is only part of one triplet of bases that codes for one amino acid therefore each codon is read as a discrete unit

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20
Q

Introns

A

non-coding sequence of DNA

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21
Q

Exons

A

sequences of DNA that code for amino acids

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22
Q

What is splicing?

A

post-transcription modification
removing introns

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23
Q

Genome

A

the complete set of genes in a cell

24
Q

Proteome

A

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

25
Q

Anticodon

A

3 bases on the tRNA which are complementary to the codon on mRNA.

26
Q

mRNA structure

A

single-stranded made up of codons a copy of one gene

27
Q

tRNA structure

A

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

28
Q

mRNA function

A

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

29
Q

tRNA function

A

a specific amino attaches at the binding site
transfers this amino acid to the ribosome to create the polypeptide chain

30
Q

Transcription

A

the first stage in protein synthesis
one gene in DNA is copied into mRNA
occurs in the nucleus

31
Q

Translation

A

the second stage in protein synthesis
the polypeptide chain is created using both the mRNA base sequence and the tRNA occurs on ribosomes in the cytoplasm

32
Q

Which enzymes are involved in transcription?

A

DNA helicase
RNA polymerase

33
Q

DNA helicase

A

catalyses the breaking of hydrogen bonds between the two strands of DNA

34
Q

RNA polymerase

A

joins adjacent RNA nucleotides
together
forming a phosphodiester bond

35
Q

pre-mRNA

A

mRNA in eukaryotes that still
contains the introns

36
Q

How is pre- mRNA modified?

A

the introns are removed by a protein called a spliceosome this leaves just the exons

37
Q

What is ATP used for in translation?

A

forming the peptide bond between amino acids

38
Q

Haploid

A

one copy of each chromosome in a cell

39
Q

Diploid

A

two copies of each chromosome in a cell

40
Q

Meiosis

A

cell division that creates
genetically different gametes
there are two nuclear divisions in this process
results in four haploid daughter cells

41
Q

Independent segregation

A

homologous pairs of chromosomes randomly line up opposite each other at the equator of the cell
when they separate it creates a large number of possible combinations of chromosomes in the daughter cells produced

42
Q

Crossing over

A

homologous pairs of chromosomes line up opposite each other at the equator in meiosis 1
parts of the chromatids twist, break and recombine with another chromatid
results in new combinations of alleles in the gametes

43
Q

Gametes

A

sex cells (sperm and egg)

44
Q

How does meiosis introduce variation?

A

crossing over independent segregation

45
Q

Types of gene mutations

A

deletion substitution

46
Q

What is a frameshift?

A

the removal of one base
changes all of the subsequent codons
all the bases shift back one position

47
Q

Chromosome mutation

A

change in the number of chromosomes
occurs during meiosis

48
Q

Deletion mutation

A

a gene mutation
a base is removed from a sequence
causes a frameshift

49
Q

Substitution mutation

A

a gene mutation
a base is swapped for a different one

50
Q

Non-disjunction

A

the chromosomes or chromatids do not split equally during anaphase

51
Q

Polyploidy

A

changes in whole sets of chromosomes
e.g. when organisms have three or more sets of chromosomes mainly occurs in plants

52
Q

Aneuploidy

A

a change in the number of individual chromosomes
e.g 3 copies of chromosome 21

53
Q

Down’s syndrome

A

causes by a chromosome mutation
an example of aneuploidy 3 copies of chromosome 21

54
Q

Genetic diversity

A

the number of different alleles in a population

55
Q

Natural selection

A

the process that leads to evolution in populations results in species becoming better adapted to their environment

Biology (5 decks)

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