3.1.1 Nucleic acids and proteins Flashcards
1
Q
nucleic acids
A
- large polymer of the class of macromolecule made of nucleotide monomers, includes DNA and RNA
2
Q
nucleotide pairing
A
A with T (double bond)
C with G (triple bond)
3
Q
no. of rings
A
C, T (pyrmidine 1)
A, G (purine 2)
4
Q
nucleotide structure
A
- phosphate group on 5’
- covalent phosphodiester bond on phosphate sugar backbond
- hydrogen bonds between strands
5
Q
condensation reaction
A
two monomers join together with peptide bond to form larger molecule producing water as byproduct
6
Q
nucleic acid function
A
stores genetic information that encodes instructions for synthesis of proteins
7
Q
polymer
A
large molecule made of small repeated monomer subunits
8
Q
monomer
A
molecule that is smallest building block of polymer
9
Q
DNA
A
- double stranded nucleic acid coils around histone proteins which form chromosomes
- deoxyribose sugar
- inherited
- long term
- thymine
10
Q
DNA function
A
stores genetic instructions for proteins and RNA
11
Q
gene
A
sequence of nucleotides in DNA that carries code to make protein
12
Q
genome
A
complete set of DNA housed within haploid set of chromosomes
13
Q
RNA
A
- single stranded nucleic acid involved in protein synthesis including mRNA, tRNA, rRNA
- ribose sugar
- temporary
- short lived
- uracil
14
Q
mRNA
A
carries complementary copy of genetic instructions in DNA to ribosomes
15
Q
tRNA
A
carries specific amino acid to ribosome after recognizing specific codon on mRNA
16
Q
rRNA
A
main structural component of ribosomes that reads mRNA sequence and links amino acids to make polypeptide chain
17
Q
universal
A
all living organisms use same codons to code for specific amino acids
18
Q
unambiguous
A
each codon only capable of coding for one amino acid
19
Q
degenerate
A
each amino acid can be coded for by different codon
20
Q
redundant
A
change to original DNA through point mutations doesn’t necessarily mean different amino acid
21
Q
non overlapping
A
each triplet/codon read independently
22
Q
genetic code
A
- universal
- unambiguous
- degenerate
- redundant
- non overlapping
23
Q
gene structure eukaryotes
A
- promoter (TATA) (one promoter for gene)
- exon/intron
- terminator
24
Q
gene structure prokaryotes
A
- promoter (one promoter can initiate transcription of many genes)
- operator
- leader
- exons
- trailer
- terminator
25
gene expression
process of reading information stored withing gene to create functional product usually proteins
26
transcription
sequence of DNA used as template to produce complementary sequence of DNA called pre-mRNA
27
transcription steps
1. - transcription factor proteins bind to promoter to initiation transcription helping RNA polymerase to bind
- weak hydrogen bonds between two DNA strands break so DNA unwinds
2. RNA polymerase moves along template strand of DNA reading nucleotide sequence and connecting free floating complementary RNA nucleotides by condensation polymerisation to produce pre-mRNA in 5'-3' direction
3. RNA polymerase detaches from DNA at termination sequence, pre mRNA released, DNA zips up
28
RNA processing
only occurs in nucleus of eukaryotes to stabilize mRNA and prevent it from degrading so it can bind to ribosomes
29
RNA processing steps
1.5' methyl guanine cap and 3' poly adenylated tail added
2. spliceosome removes introns and splices exons together
30
alternative splicing
allows single gene to create many different mRNA strands
31
translation
mRNA sequence is read to produce corresponding polypeptide chain
32
translation steps
- mRNA exits nucleus and travels to ribosome
1. 5' end of mRNA read until start codon where tRNA molecule with complementary anticodon binds to ribosome and delivers specific amino acid
2. this process continues, amino acids binding to adjacent amino acid with peptide bond via condensation reaction
3. continues until stop codon read by ribosome and polypeptide chain released by hydrolysis
- at ER and golgi, polypeptide folded and modified into fully functioning protein which remains in cell or exported by exocytosis
33
gene regulation
inhibiting or activating gene expression to conserve energy by preventing over/under production
34
structural genes
- code for proteins involved in structure/function of cell/organism
- enzymes, transport proteins, receptors, peptide hormones
- 3' end
35
regulatory genes
- produce regulatory proteins like repressor and activator proteins that that turn gene expression on or off or decrease/increase rate by promoting or hindering transcription
36
repressor protein
coded by regulatory gene preventing gene expression by binding to operator sequence and stopping RNA polymerase from transcribing genes
37
activator protein
increases gene expression by binding to promoter encouraging RNA polymerase to bind
38
operon
in prokaryotes, multiple structural genes controlled by a single promoter and operator with common purpose
39
gene reg reasons
- energy and resource conservation
- responding to changing environment by controlling metabolic pathways
- in multi cellular organisms, differentiating cell function
40
trp operon
structural genes code for enzymes which make amino acid trp
41
repression (high trp)
- two trp molecules bind to repressor protein inducing change to 3D shape of repressor protein allowing it to become active and bind to operator
- prevents RNA polymerase binding to promoter and transcribing structural genes
42
repression (low trp)
- trp doesn't bind with repressor meaning repressor protein remains in inactive shape and doesn't bind to operator
- RNA polymerase can bind to promoter to continue transcribing structural genes
43
proteome
all proteins expressed by genome of cell or organism at particular time
44
protein functions
enzymes, transport, structural, hormones, receptors, defence, motor/contractile, storage
45
enzymes
organic catalysts that speed up chemical reactions
46
amino acids
- central carbon atom, carboxyl group, amino group, R group, H atom
- each R group has different chemical properties such as hydrophilic or hydrophobic
- condensation reaction at ribosome forms strong covalent peptide bonds to join amino acid monomers into polypeptide
47
primary structure
sequence of amino acids in polypeptide
48
secondary structure
- polypeptide chain folds and coils by forming regular hydrogen bonds between amino acid amine and carboxyl groups
- alpha helix, beta pleated sheets, random coil
49
tertiary structure
- overall functional 3D shape of protein (functional proteins have minimum tertiary structure)
- irregular ionic, H, covalent bonds between R groups
50
quaternary structure
- two or more polypeptides of tertiary structure joined together
- can have prosthetic group (non protein) attached
51
diversity of proteins
amino acid sequence influences tertiary and quaternary structures so functional diversity arises due to ability to create unlimited combinations of amino acids
52
effect of change of original sequence
- errors in reading code, exposed to high temp/salt/acidic/alkaline solutions may change unique shape and prevent protein from functioning correctly (large changes can denature proteins permanently)
53
protein secretory pathway
1. ribosome: synthesises protein (if on RER, destined to be secreted)
2. rough ER: allows correct folding of newly formed polypeptides
3. transport vesicle: buds off rought ER and travels to golgi to fuse and release protein into lumen
4. golgi: proteins can have chemical groups added or removed then packaged into secretory vesicles for export out of cell or released into cytosol of cell
5. secretory vesicle: buds off golgi and travels to semi permeable plasma membrane for exocytosis
54
exocytsosis
- form of bulk (moving large molecules by vesicle into/out of cell) and active (requires input of energy) transport
- possible due to fluidity of plasma membrane
55
exocytosis process
1. vesicle containing secretory products transported to cell membrane
2. membrane of vesicle fuses with cell membrane
3. secretory products released from cell into extracellular environment
56
globular proteins
- single chains or several polypeptide chains folded (primary or quaternary)
- spherical shape
- dissolve easily in water (soluble)
- functional: catalytic, regulatory, transport, defense (e.g. hemoglobin)
57
fibrous
- parallel polypeptides in long fibres/sheets
- long shapes
- physically tough but able to stretch
- insoluble
- structural: contractile (e.g. collagen)
58
denaturing
- high temperatures break hydrogen bonds breaking the tertiary and quaternary structure of proteins
- un optimal ph break ionic bonds breaking the tertiary and quaternary structure of proteins
