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Biology > Genetic > Flashcards

Genetic Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Eukaryotic DNA

A

Long linear chromosones
DNA in nucleus
DNA tightly wrapped around proteins called histones

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2
Q

Prokaryotic DNA

A

Supercoiled - condenses circular chromosones so they can fit inside the cell
Short and circular

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3
Q

Bases of DNA

A

Adenine
Guanine
Cytosine
Thymine

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4
Q

Locus

A

Specific physical location of a gene or other DNA sequence on a chromosone

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5
Q

Exons

A

Coding regions in a gene

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6
Q

Introns

A

Non coding regions in a gene

Removed during splicing

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7
Q

Features of the genetic code

A

Degenerate
Universal
Non - overlapping

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8
Q

Degenerate

A

More than one codon can code for the same amino acid

64 possible triplet codes but 20 amino acids

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9
Q

Universal

A

Same four bases (A,T,C,G) are used in the DNA of every organism
Codons in DNA are transcribed into mRNA and translated into amino acids in every organism

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10
Q

Non - Overlapping

A

No overlapping between triplet codes

Each triplet is separate from other triplets

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11
Q

Substitution mutation

A

One base is substituted for another

eg. ATCCGT - ACCCGT

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12
Q

Name the 3 types of substitution mutation

A

Silent
Misense
Nonsense

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13
Q

Silet mutation

A

Base changes but doesn’t change the amino acid

eg. UCU = Serine , UCC = Serine

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14
Q

Misense mutation

A

Base changes and it changes the amino acid (alters binding site)
eg. AAG = Lysine , AGG = Arginine

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15
Q

Nonsense mutation

A

Base changes and alters amino acid to have a stop codon (anticodon) that is complementary
eg. UCU = Cystine , UGA = Stop
Stops DNA replicating

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16
Q

Name the two types of frameshift mutation

A

Deletion

Insertion

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17
Q

Deletion

A

One base is deleted
Causes codons to change which results in different amino acids
Changes the primary structure of a protein which results in a potentially whole different protein / faulty - leads to disease

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18
Q

Insertion

A

A base is added

Changes the amino acid sequence

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19
Q

How do mutagenic agents work

A

Increase the frequency of a mutation occurring
Act as a base
Alter a base
Change structure of DNA

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20
Q

Name the 3 mutagenic agents

A

Xray
Ionising radiation
Chemicals

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21
Q

What are the effects of mutation

A

Production of new/superior protein - results = gain of reproductive advantage
Neutral mutation - results = no change
Production of an inferior / no protein - result = fatal/ disease killing

22
Q

Causes of mutation

A

A mutation can occur by mistake during DNA replication - spontaneously occur
DNA polymerase makes a mistake about once every 100,000,000

23
Q

Transcription

A

Occurs in the nucleus

24
Q

Transcription - Initiation

A

RNA polymerase attaches to the beginning of the DNA code - Promoter
The DNA molecule unwind and the weak hydrogen bonds between the complementary strands break
One strand now acts as a template for the formation of the mRNA strand

25
Q

Transcription - Elongation

A

Free nucleotides in the nucleus bond to the complementary baes of the DNA template (Uraci replaces Thymine in mRNA)
More free nucleotides bond to their complementary bases , to elongate the mRNA strand , until the entire code has been transcribed
The RNA polymerase joins the nucleotides in condensation reactions (forms phosphodiester bonds)

26
Q

Transcription - Termination

A

The mRNA will detach from the DNA template
The RNA polymerase detaches and starts all over again at a different location where needed
Now the pre-mRNA strand has to undergo modification and RNA splicing before it can leave the nucleus

27
Q

Splicing

A

RNA splicing removes introns (non coding RNA) and joins exons (coding RNA)
Creates a mRNA molecule with continuous coding sequence

28
Q

RNA

A

Ribonucleic acid
Single stranded
Consists of - pentose sugar (ribose) , phosphate group, base (A,U,C,G)

29
Q

mRNA

A

Transfers the DNA code from nucleus to cytoplasm
Complementary to DNA code
Small enough to leave nucleus pore
Single stranded

30
Q

tRNA

A

Small
Single stranded - folded into a clover leaf shape
Amino acid at top , Anti codon at bottom

31
Q

Translation

A

A cell translates mRNA message into polypeptide

32
Q

Translation - Initiation

A

Small ribosomal subunit binds with mRNA
Small subunit moves along mRNA until it reach the start codon (AUG)
The matching anti codon of the tRNA (with amino acid) bonds with start codon
Large ribosomal subunit is added - complete translation initiation complex

33
Q

Translation - Elongation

A

More tRNA anticodon attach to mRNA codons
The amino acids attached to the tRNA’ attach to one another by peptide bonds
Amino acid form a long polypeptide chain
tRNA releases Amino acids to pick up more amino acids

34
Q

Translation - Termination

A

Occurs when a stop codon in the mRNA reaches the active site of a ribosome
Releases polypeptide

35
Q

Meiosis

A

Only takes place in sex organs - produces gametes
Starts with a diploid cell - results in 4 identical haploid cells
Contain individual chromosomes - not pairs

36
Q

Homologus chromosones

A

One from mother and one from father
Both chromosones in a homologous pair have the same genes
Can inherit different alleles from each parent

37
Q

Meiosis 1

A

Homologous chromosomes are separated from each other

38
Q

Meiosis 2

A

Sister chromatids separated from each other

39
Q

Meiosis - Interphase

A

Before meiosis the cell will have been through interphase
During interphase - cell copies chromsones and organelles
Chromosones not visible as distinct structures in interphase

40
Q

Prophase 1

A

Chromosones condense and become visible
Homologous chromosones link together forming chiasmata
Crossing over takes place - exchanging alleles between homologous chromosones
Nuclear membrane breaks down

41
Q

Metaphase 1

A

Homologous pairs of chromosones now line up along the equator

42
Q

Anaphase 1

A

Spindle fibres shorten and homologous chromosones move to opposite poles
Chiasmata between homologous chromosones breaks

43
Q

Telophase 1

A

Chromosones now reached poles of cell

Nuclear membrane reforms and chromosones move to opposite poles

44
Q

Cytokinesis 1

A

Divides into 2 cells

Haploid

45
Q

Cytokinesis 1

A

Divides into 2 cells

Haploid

46
Q

Prophase 2

A

Chromosones condense and become visible again

Nuclear membrane breaks down and spindle fibres begin to develop

47
Q

Metaphase 2

A

Chromosones are lined up on the equator

48
Q

Anaphase 2

A

Centromere of each chromosome divides
Spindle fibres shorten
Chromatids pulled apart to opposite poles of cell

49
Q

Telophase 2

A

Chromatids have reached the poles of the cell
Chromosomes
Nuclear membrane reforms and chromosones coil back to chromatid state

50
Q

Cytokinesis 2

A

Produces 2 haploid cells

Biology (6 decks)

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