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Biology > DNA, Genes and Chromosomes > Flashcards

DNA, Genes and Chromosomes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

do eukaryotes have introns?

A

yes

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2
Q

do prokaryotes have introns?

A

no

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3
Q

In mitochondria + chloroplasts in eukaryotic cells, DNA is…

A
  • short
  • circular
  • not associated with proteins
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4
Q

a chromosome is made up of…

A

DNA molecule associated with histone proteins

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5
Q

when do chromosomes become visible?

A

prophase

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6
Q

How is DNA packed into a chromosome?

A
  1. DNA double helix
  2. DNA + histones
  3. DNA - histone complex coiled
  4. Loops coil/pack together
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7
Q

Give the definition of homologous pairs

A

pairs of chromosomes, 1 maternal and 1 paternal set. Contain the same genes in the same loci but are not genetically identical as they have different alleles

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8
Q

what is the equation to remember the creation of a diploid cell from 2 haploids

A

n (23) + n (23) = 2n (46)

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9
Q

definition of allele

A

alternative form of a gene

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10
Q

characteristics of alleles?

A
  • inherit/display at least 1 allele from either mum/dad
  • when alleles same = code for same polypeptide
  • alleles different = code for different poly.
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11
Q

what is genotype and phenotype?

A 
geno = genetic code 
pheno = characteristics (combination of proteins interacting with environment)
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12
Q

definition of mutation

A

changes to the base sequence of a gene produces a new allele for that gene

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13
Q

mutations can cause…

A
  • a different polypeptide produced
  • may not function properly or not at all
  • i.e. if it was an enzyme, 3D active site changes shape, substrate no longer fits
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14
Q

definition of a gene

A

base sequence of DNA that codes for:

  • amino acid sequence of a polypeptide
  • functional RNA
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15
Q

definition of locus

A

a gene that occupies a fixed position in a particular DNA

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16
Q

Definition of intron and exons

A 
in = non-coding DNA 
ex = coding DNA (separated by 1 or more introns)
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17
Q
  1. there are __ naturally occurring amino acids.
  2. _ bases code for _ amino acid = a _______
  3. _ bases produce __ triplets = some amino acids are coded by more than 1 ____
A
  1. 20
  2. 3, 1 = triplet
  3. 3, 64 = triplet
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18
Q

definition of degenerate code

A

all but 2 amino acids are coded by more than 1 triplet

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19
Q

definition of non-overlapping

A

each triplet is only read once

20
Q

definition of universal

A

each triplet codes for the same amino acid in all organisms

21
Q

definition of genome

A

complete set of genes in a cell (including mitochondria/chloroplasts)

22
Q

definition of a proteome

A

full range of proteins that can be produced by a cell

23
Q

definition of a codon

A

sequence of 3 bases on mRNA that codes for a single amino acid

24
Q

what is the shape of tRNA compared to mRNA?

A 
t = folded clover leaf shape 
m = single helix
25
Q

tRNA and mRNA are both…

A

single stranded nucleotide chains

26
Q

which one is less chemically stable t or mRNA?

A

mRNA - broken down in a few days

27
Q

What is tRNA complementary to?

A

has complementary anticodons to the codons on the mRNA

28
Q

what is mRNA complementary to?

A

has complementary codons to the triplets on DNA

29
Q

Name the 2 steps of protein synthesis

A
  1. transcription: production of mRNA (DNA transcribed into mRNA)
  2. translation: production of poly. using sequence of codons. Occurs in ribosomes
30
Q

what does RNA helicase do?

A
  • unwinds section of DNA (breaks hydrogen bonds)

- exposes the gene that needs to be transcribed

31
Q

what does RNA polymerase do?

A
  • attaches to template strand

- joins complementary RNA molecules together

32
Q

What is formed in transcription?

A

pre-mRNA

33
Q

In prokaryotes transcription forms ______ not __-_____ as there are no ____ present. So _____ does not occur.

A

mRNA, pre-mRNA, introns, splicing

34
Q

What occurs only in eukaryotes?

A

splicing

35
Q

describe splicing

A
  1. pre-RNA = introns + exons
  2. introns prevent synthesis of poly.
  3. base sequences corresponding to these introns removed
  4. then replaced with functional exons
36
Q

how does mRNA leave the nucleus

A

via nuclear pores

37
Q

tRNA has a specific _______ and attaches to a specific amino acid via the amino acid ________ ___.

A

anticodon, attachment site

38
Q

does translation need energy?

A

yes - in the form of ATP hydrolysis

39
Q

definition of a polysome

A
  • multiple ribosomes working simultaneously along a strand of mRNA,
  • increases rate of synthesis + protein yield
40
Q

Stages of translation:

  1. mRNA associates with ribosome in ________
  2. first 2 codons on ribosome attract complementary ______
  3. ______ on tRNA join via __________ base pairing (forms ______ bonds with codons)
  4. _____ bond formed between __ amino acids (catalysed by ______ transferase)
  5. ribosomes move forward by 1 codon
  6. first tRNA leaves ribosome, new one enters carrying 3rd codon
  7. another ______ bond forms (between second and new amino acid) = forms _________
  8. ribosome moves along until reaching _____ codon and then detaches (presence of release ____)
  9. _________ chain released ______ into correct shape
A
  1. cytoplasm
  2. tRNA
  3. anticodons, complementary, hydrogen
  4. peptide, 2, peptidyl
  5. peptide, polypeptide
  6. stop, factor
  7. polypeptide, folding
41
Q

In prokaryotic cells: DNA molecules are _____, circular and not associated with ______.

A

short, proteins

42
Q

In the nucleus of eukaryotes: DNA molecules are very long, ______ and associated with proteins, called_____.

A

linear, histones

43
Q

what is the definition of a triplet?

A

A sequence of three DNA bases which codes for a

specific amino acid

44
Q

chromosomes have 2 _______ joined by the ________. The 2 ______ are identical copied

A

chromatids, centromere, chromatids

45
Q

how many chromosomes do humans have in each somatic cell?

A

46

Biology (25 decks)

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