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Biology 3/4 > chapter 2 (nucleic acids and proteins) > Flashcards

chapter 2 (nucleic acids and proteins) Flashcards

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1
Q

Protein functional diversity

A
  • proteins form many different functions
    e.g structural support, transport, enzymes, defence and hormones
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2
Q

Monomers of proteins and nucleic acids

A

proteins = amino acids
nucleic acids = nucleotides

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3
Q

amino acid structure

A
  • amino group
  • central carbon
  • carboxyl group
  • r-group
    (r-group is specific for each of the 20 amino acids)
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4
Q

Condensation reactions

A
  • joins the amino acids together
  • forms phosphodiester bonds
  • releases by-products (water)
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5
Q

Protein structure levels - primary

A
  • sequence of amino acids in a polypeptide chain
  • written as three letter codes
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6
Q

Protein structure levels - secondary

A
  • arrangement into alpha helices, beta pleated sheets and random coils
  • polypeptide chain folds and coils
  • structure is held with hydrogen bonds
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7
Q

Protein structure levels - tertiary

A
  • functional 3D shape of a protein
  • secondary structures may fold and join together
  • disulphide bonds further stabilise 3D structure
  • protein must at minimum have a tertiary structure to function
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8
Q

Protein structure levels - quaternary

A
  • bonding of multiple polypeptide chains with a tertiary structure together
  • held together by hydrogen bonds
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9
Q

haemoglobin

A
  • quaternary structure
  • composed of 4 polypeptide chains bonded together
  • carries oxygen in red blood cells
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10
Q

Structure of DNA

A
  • two polynucleotides chains run antiparallel (3’ to 5’) and (5’ to 3’)
  • joined together via complementary base pairing (A & T) (C & G)
    (A & T = 2 hydrogen bonds)
    (C & G = 3 hydrogen bonds)
  • phosphate added at 5’ end
  • OH added at 3’ end
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11
Q

rnucleic acid structure & primers

A
  • phosphate (circle)
  • five-carbon sugar (pentagon)
  • nitrogenous base (rectangle)
  • 1’ attaches to nitrogenous base
  • 5’ attaches to sugar phosphate group
  • 3’ attaches to phosphate of following nucleotide)
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12
Q

Purines and pyrimidines

A

purines = adenine & guanine
(2 nitrogen carbon rings)
pyrimidines = thymine & cytosine
(1 nitrogen carbon ring)

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13
Q

different types of RNA

A

mRNA - messenger RNA: carries genetic information from nucleus to ribosomes for protein synthesis

tRNA - transfer RNA: delivers specific amnio acids to the ribosome after recognising specific nucleotide sequence

rRNA - ribosomal RNA: serves as main structural component of ribosomes

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14
Q

DNA v RNA similarities and differences

A

similarities:
- same basic structure (phosphate, sugar and nitrogen base)
- contain adenine, guanine & cytosine
- contain sugar-phosphate backbone
differences:
DNA - double stranded
- deoxyribose sugar
- thymine
- inherited and long-term storage
RNA - single stranded
- ribose sugar
- uracil
- temporary and short-lived molecule

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15
Q

Translation table

A
  • first base, second base, third base
  • START CODON: AUG (met) is always the start codon
  • STOP CONDONS: UAA, UAG, UGA
    (do not code for a amino acid)
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16
Q

exons, introns & operator

A

exons - regions of coding DNA (in both prokaryotes & eukaryotes)
introns - regions of non-coding DNA (in eukaryotes)
operator - serves as binding site for repressor (in prokaryotes)

17
Q

key genetic code

A

unambiguous: codon is only capable for coding one specific amino acid
degenerate: each amino acid may be coded for by multiple different codons
non-overlapping: each codon is read independently without overlapping
universal: nearly every organism uses the same codon to code for a specific amino acid

18
Q

types of gene

A

constitutive - genes that are always switched on (what we need)(e.g blood and growth)

regulatory - control the expression of other genes, does not code for a protein, turn structural genes off or on

structural gene - codes for RNA or protein, achieves an effect within the organism, producing useful proteins
(e.g structural protein, enzyme, RNA molecule)

19
Q

3 stages of transcription

A
  • copying of DNA code
  • first stage of expression and creation of pre-mRNA and occurs in the nucleus
    INITIATION:
  • RNA polymerase binds to the promoter region
  • DNA unwinds
    ELONGATION:
  • RNA polymerase reads the DNA template strand and uses complementary RNA nucleotides to catalyse the formation of pre-mRNA
  • strand of DNA that is not read is called the coding strand
    TERMINATION:
  • transcription is terminated when the termination sequence is recognised
  • pre-mRNA is then processed to become mRNA
20
Q

RNA proccesing

A
  • ‘editing’ and ‘proofreading’
  • post-transcriptional modifications
  • occurs in the nucleus
    5’METHYL-GCAP & 3’ POLY-ATAIL:
  • serves to stabilise the mRNA molecule
  • prevents degrading
  • allows it to bind to ribosomes
    SPLICING:
  • introns non-coding regions of DNA (are removed)
  • exons coding regions of DNA
    (must be joined together)
  • splicing occurs via spliceosomes
    ALTERNATIVE SPLICING:
  • sometimes exons can also be removed
21
Q

3 stages of translation

A
  • reading and converting mRNA into a polypeptide chain
  • occurs in the ribosome
    INITATION:
  • mRNA molecule binds to the ribosomes
  • tRNA complementary to mRNA deliver corresponding amino acids to the ribosome
    ELONGATION:
  • adjacent amino acids are joined with peptide bonds via a condensation reaction to form a polypeptide
    TERMINATION:
  • translation ends when a STOP codon is recognised
22
Q

promoter & operator

A

promoter: binding site for RNA polymerase (recognition site)
operator: binding site of repressor protein

23
Q

repression

A

LOW LEVEL OF TRYPTOPHAN:
- insufficient tryptophan to bind to repressor protein
- causes repressor protein to detach from operator region
- allowing RNA polymerase to transcribe the trp gene and increase tryptophan levels
HIGH LEVEL OF TRYPTOPHAN:
-sufficent tryptophan to bind to the repressor protein
- causing conformational change and repressor protien to stay attached
- RNA polymerase will not transcribe the trp gene and no tryptophan will be produced

24
Q

attenuation

A
  • transcription and translation occur simultaneously
    LOW LEVEL OF TRYPTOPHAN:
  • due to no tRNA bound tryptophan in cell ribosomes pause
  • causes mRNA molecule to fold and form anti-terminator hairpin loop
  • RNA polymerase continues and transcribes genes to synthesise tryptophan
    HIGH LEVEL OF TRYPTOPHAN:
  • tRNA bound tryptophan travels to ribosomes and is added to proteins
  • causes mRNA to fold and form terminator hairpin loop
  • causes mRNA to seperate and RNA polymerase to detach stop transcription and no new tryptophan to be synthesised
25
Q

exocytosis

A
  • secretory products transported to plasma membrane via vesicles
  • membrane of vesicles fuse with the plasma membrane
  • secretory products are released from the cell
26
Q

protein secretory pathway

A
  • ribosomes, rough endoplasmic reticulum, transport vesicle, golgi apparatus, secretory vesicles

Biology 3/4 (10 decks)

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