Lecture 7/8-Nucleic Acids + Protein Synthesis Flashcards
1
Q
Describe nucleic acids?
A
Where organism store PROTEIN STRUCTURE information in macromolecules
2
Q
How is information stored in nucleic acids passed on to daughter cells?
A
During cell divison
3
Q
What do nucleic acids serve as?
A
STORAGE UNITS for our unique hereditary info
4
Q
What does DNA contain?
A
Necessary information to make proteins
5
Q
What is the function of RNA?
A
TRANSLATES the info found in DNA
6
Q
Name 2 polynucleotides?
A
DNA + RNA
7
Q
What are the 3 building blocks of a nucleotide?
A
- Sugar (ribose/2-deoxy ribose)
- Nitrogenous base
- Phosphate group
8
Q
What is a nitrogenous base?
A
Nucleobase
9
Q
What is a nucleoside?
A
Nucleobase + sugar
10
Q
What is a nucleotide?
A
Nucleoside + sugar + phosphate
11
Q
How is a nucleotide normally named after?
A
Its nucleobase
12
Q
If a nucleotide has 2 / 3 additional phosphates, what would you call them?
A
- Nucleotide diphosphate
- Nucleotide triphosphate
13
Q
Can nucleotides be cyclic
A
YES
14
Q
How do you form a nucleoside?
A
Attach a sugar with a beta-N-glycosidic link
15
Q
What is Adenosine formed from?
A
The nucleobase adenine + ribose
16
Q
What two forms can nucleobases be?
A
Pyrimidines / purines
17
Q
What defines a nucleobase as pyrimidine?
A
Heterocyclic organic compounds consisting of a pyrimidine ring
18
Q
Name 3 pyrimidine nucleobases?
A
Cytosine , Uracil , Thymine
19
Q
What defines a nucleobase purine?
A
Heterocyclic organic compounds consisting of a pyrimidine ring FUSED to an imidazole ring
20
Q
Name 2 purine nucleobases?
A
Adenine / Guanine
21
Q
Name 2 multiphosphroylated nucleotides?
A
ATP / GTP
22
Q
Name the other deoxy forms of DNA
A
dATP / ddATP
23
Q
What is NAD+?
A
A co-enzyme involved in cellular reactions
24
Q
What is the phosphorylated form of NAD+?
A
NADP+
25
What do NAD+ + NADP+ act as?
E- acceptors (oxidising agents)
26
How can cyclic AMP be produces?
By ADENYLATE CYCLASE
27
What is cAMP important in?
A cell signalling molecule
28
What can you do to ATP in order to release energy?
DEPHOSPHORYLATED
29
What is GTP important in?
Protein synthesis + cell signalling
30
What is DNA ?
A polymer made from nucleotides
31
How is the sugar-phosphate backbone formed?
The phosphate on 1 nucleotide COVALENTLY LINKS via a PHOSPHODIESTER BOND to the 2-deoxy ribose sugar on the next one
32
What protrudes from each sugar unit?
The Nitrogenous bases
33
How is the double helix of DNA formed?
2 strands twist around each other
34
How are the 2 DNA strands complementary to each other?
Orientation + nitrogenous bases
35
Who discovered the DNA structure?
Watson + Crick 1953
36
Are DNA strands parallel or antiparallel?
Antiparallel
37
How are strands read?
from 5' to 3'
38
What types of ends do complementary strands?
asymmetric ends
39
What are genes?
Portions of DNA
40
What is the function of DNA?
They carry the instructions for making proteins
41
What do the order of bases determine?
The order of AA in the protein (genetic code)
42
What do proteins determine?
Cell structure, function, identity
43
What is a Karyotype?
The number + appearance of chromosomes in the nucleus of a eukaryotic cell
44
What are the differences between DNA + RNA?
Ribose vs Deoxyribose
Single-stranded vs Double-stranded
Uracil vs Thymine
45
What is the role of mRNA?
Converts the genetic info in DNA ----> template used to construct a protein molecule
46
What is the role of tRNA?
Help transport AA that build the polypeptide chain of a protein
47
What is the role of rRNA?
Makes up the ribosomes (the organelles that translate the mRNA)
48
What is the central dogma?
Information in nucleic acid can be perpetuated / transferred , but the transfer of info into protein is IRREVERSIBLE
49
What are the 4 uses of DNA?
- Forensic DNA "fingerprint" analysis
- DNA sequencing + somatic gene therapy
- Genetic engineering to make/change proteins (insulin)
- Gene editing using CRISPR
50
What breaks apart the DNA strands?
RNA POLYMERASE
51
H ow is a single strand of mRNA transcribed from the template strand?
Using the base pair rule
52
Where are the required nucleotides found used in mRNA synthesis?
Freely in the nucleus
53
How is the pre-mRNA cap formed?
From phosphorylated 7-methyl guanosine via guanylyltransferase
54
What dies the 5' pre-mRNA cap ensure?
- The mRNA is exported out of the nucleus
- Blocks degradation via 5' exonucleases
- Promotes translation
55
How is the pre-mRNA 3' poly-A-tail formed?
- The pre-mRNA = cleaved by an endonuclease near a signal AAUAAA sequence at the 3' end
- appr.200 adenosine residues are added by poly-A polymerase
56
What does the 3' poly-A-tail do in the pre-mRNA?
- Protects the mRNA from degradation by 3' exonucleases
- aids in termination of transcription
- ensures export from the nucleus
- important in translation
57
What does alternative splicing of pre-mRNA do?
Produce different proteins from the SAME gene
58
What does a mature mRNA consist of?
- 5' cap
- 5' UTR (untranslated region)
- Coding Region (translated into protein)
- 3' UTR
- Poly-A-tail
59
What regulates the function of mature mRNA?
The 3' UTR
60
What are the different types of AA?
- Small
- Nucleophilic
- Hydrophobic
- Aromatic
- Acidic
- Amide
- Basic
61
What do DNA base triplets represent?
Each AA
62
What are base triplets in mRNA called?
Codons
63
How many AA and mRNA codons are there?
AA=20
| mRNA codons= 64 (4^3)
64
What does the degenerate code mean?
More than 1 codon codes for each of the 20 AA
65
What parts of the codon are the most important?
The 1st 2 bases
66
What does the degeneracy of the genetic code help with?
Gives tolerance against mutations
67
What is the start codon?
AUG (methionine)
68
What are the stop codons?
UAG
UAA
UGA
69
Describe the mutation in Sickle cell anaemia?
The change in AA sequence = haemoglobin to CRYSTALLISE when O2 levels are low, causing the sickle shape
70
What does the accumulation of sickle cells in small blood vessels show?
- Downstream tissue ischaemia = pain +infarction
| - Severe cases = organ damage + ischaemic stroke
71
Where is the DNA code transcribed into mRNA?
In the nucleus
72
Where does protein synthesis occur?
OUTSIDE the nucleus
73
What are ribosomes composed of?
-Ribosomal RNA + ribosomal proteins
74
What are the components of a ribosome?
60s subunit + 40s subunit
75
What do tRNAs have that allow them to match up to the mRNA code?
Complementary base triplets
76
Is there a tRNA for each codon?
YES
77
What are attached to tRNA molecules?
AA
78
How are AA assembled in the correct sequence?
The matching of tRNA + mRNA
79
tRNA bound ----> AA = ?
Aminoacyl tRNA / charge tRNA
80
tRNA molecule with AA removed = ?
Deacylated / uncharged tRNA
81
tRNA molecule bound ----> growing polypeptide chain = ?
Peptidyl tRNA
82
What is initiation?
Binding of ribosome to 5' end of mRNA + H binding of the anticodon of an aminoacylated tRNA carrying methionine on the AUG start codon
83
What is elongation?
- The addition of further AA to the growing polypeptide chain brought by corresponding aminoacylated tRNAs
- Peptidyl transferase creates covalent peptide bonds between AA
84
What is termination?
When the stop codon is reached+ the peptide and the ribosomal subunits are released
85
If a protein has to go to the cytoplasm, where is it synthesized?
Free ribosomes
86
If a protein has to go to be secreted out of the cell , where is it synthesized?
On the ribosomes attached to the RER
87
What is the RER?
A system of flattened cavities
88
What is the RER lined with?
By a thin membrane running from the nuclear envelope into the cytoplasm + studded with ribosomes
89
What does the RER provide for protein synthesis?
Compartment
90
What do secreted proteins have that interact with the RER membrane?
Special signal sequences
91
What are vesicles?
Small spherical compartments made from the RER membrane
92
How are secreted proteins incorporated for transport to the Golgi complex?
Into vesicles
93
What is the Golgi complex?
A system flattened plate-like cavities
94
What is the GA lined by?
A thin membrane
95
What happens in the GA cavities?
Post-translational modification of protein e.g. glycosylation of membrane spanning proteins
96
After the vesicles move to the golgi apparatus + post-translational modification occurs, what happens next?
- The now modified protein TRAVERSES the GA + is packaged into secretory vesicles
- They then move + fuse + expel contents into the extracellular space (exocytosis) at the cell membrane
97
What are specialised GA vesicles called?
Lysosomes
| -contain enzymes that digest old organelles
