proteins and nucleic acids

Question 1

what are nucleic acids?

Answer 1

information macromolecules that encode instructions for the synthesis of proteins
- large, linear polymers

Question 2

what is the role of nucleic acids?

Answer 2

store and transmit genetic info

Question 3

what are nucleotides?

Answer 3

monomers of nucleic acids

Question 4

what is rna and its role?

Answer 4

involved in decoding genetic info from DNA
- usually single-stranded ribose sugar phosphate linked together by nucleotides

specify type of sugar (ribose)

Question 5

what is mrna and its role?

Answer 5

messenger rna: transcribed from dna in nucleus
- carries copy of genetic instructions for protein synthesis to ribosomes in cytoplasm

Question 6

what is rrna and its role?

Answer 6

ribosomal rna: rna strand that binds to proteins to form ribosomes that assembles amino acids

Question 7

what is trna and its role?

Answer 7

transfer rna:
- carries specific amino acids to the ribosome

Question 8

DUUN

what are the properties of the genetic code?

Answer 8

• degenerate
• universal
• unambiguous
• non-overlapping

Question 9

describe the universal property of the genetic code

Answer 9

nearly all organisms use the same codon to code for specific amino acids

Question 10

describe the unambiguous property of the genetic code

Answer 10

each codon is only capable of coding for one specific amino acid

Question 11

describe the degenerate property of the genetic code

Answer 11

each amino acid may be coded for by multiple different codons

Question 12

describe the non-overlapping property of the genetic code

Answer 12

each triplet or codon is read independently, without overhanging to adjacent triplets or codons

Question 13

what is gene expression?

Answer 13

process of reading the info stored within a gene to create a functional product (typically a protein)

always specify which dna strand ur talking about

Question 14

what is transcription?

Answer 14

create a complementary strand of mrna from info stored in dna template strand

Question 15

outline the process of transcription

Answer 15

• rna polymerase catalyses transcription of dna template strand into pre-mrna
• binds to the promoter region and travels along dna unwinding/unzipping it to expose bases
• joins free-floating complementary rna nucleotides to dna template strand using uracil instead of thymine to pair w adenine
• rna polymerase travels along dna until it reaches termination sequence

Question 16

what is mrna editing?

Answer 16

pre-mrna made during transcription is modified before it leaves the nucleus

only in eukarys: prokarys only have exons that are directly translated

Question 17

what is the purpose of modifications to the 5’ and 3’ ends of pre-mrna?

Answer 17

mrna exits the nucleus can remain stable long enough to be translated

Question 18

what does the 5’ methly-G cap do?

Answer 18

stop degradation during transport from the nucleus

Question 19

what does the poly-a-tail do?

Answer 19

• protecti mrna from degradation
• provide stability to mrna

Question 20

advantages of splicing?

Answer 20

• alternative splicing: exons spliced together in different ways/different exon combos= create variations in the translated protein

Question 21

what is translation?

Answer 21

process that uses mrna to make a polypeptide chain

Question 22

outline the process of translation

Answer 22

• ribosome binds to and reads the mRNA molecule
• tRNA anticodons are complementary to the mRNA codons
• tRNA brings the corresponding amino acids to the ribosome
• adjacent amino acids are joined together into a polypeptide chain via a condensation reaction.

ends when stop codon recognised

Question 23

what is gene regulation and the purpose of it?

relate to trp operon

Answer 23

turning genes off and on
- increase or decrease production of specific products

controls expression of genes in trp operon

Question 24

what is the advantage of gene regulation?

relate to trp operon

Answer 24

• does not produce unnecessary proteins= cells save more energy
• production of the proteins coded for by the trp operon occurs only when necessary= ensures cell is never completely w/o trp

Question 25

what are regulatory genes?

Answer 25

dna sequences that code for proteins that control the expression of other genes | eg. repressor proteins, activator proteins

Question 26

what are structural genes? | relate to trp operon

Answer 26

dna sequences that code for proteins that are not regulatory proteins - responsible for producing proteins that form the stucture or facilitate functioning of organism - code for proteins that will make trp

Question 27

what is an operon?

Answer 27

set of adjacent genes and nearby regulatory sequences that affect transcription of the genes

Question 28

what is the trp operon?

Answer 28

group of genes found in e.coli - code for enzymes that make the amino acid tryptophan and the regulatory sequences that control their expression | regulated by trp repressor protein

Question 29

what are the gene regulation mechanisms? | 2

Answer 29

- repression: repressor protein stop the initiation of transcription when trp lvls are high - attenuation: premature ceasing of translation stops transcription when trp lvls are relatively high

Question 30

what is the promoter region?

Answer 30

binding site for rna polymerase - denotes the starting position of transcription

Question 31

what is the operator region?

Answer 31

binding site for proteins that control gene expression

Question 32

what is the role of the repressor protein? | relate to trp

Answer 32

decrease/stop gene expression - prevents rna polymerase from transcribing the structural genes

Question 33

what is the purpose of attenuation?

Answer 33

additional layer of gene regulation - transcription and translation begins but does not finish -> stops before any actual proteins are made | ribosome is involved

Question 34

what makes each of the amino acids unique in a protein unique?

Answer 34

- r-group uniquely determines the identity of a particular amino acid - unique chemical properties affect how amino acids with interact and fold up with others

Question 35

what is the primary structure of a protein?

Answer 35

sequence of amino acids in a polypeptide chain - order of nucleotides in the dna sequence

Question 36

what is the secondary structure of a protein?

Answer 36

polypeptide chain folds and coils by forming h bonds b/w amino acids of different sections - random coils join ⍺-helicies and β-pleated sheets

Question 37

what is the tertiary structure of a protein?

Answer 37

secondary structures folds due to distant sections of polypeptide chain interacting/repulsing - 3d shape formed and maintained by side chain bonds: bonding and interactions b/w r-groups

Question 38

what is a quatenary structure in a protein?

Answer 38

2 or more polypeptide chains w tertiary structures join together | pp chains w 3rd structure that have non protein group= 4th structure

Question 39

what structure do most proteins become functional?

Answer 39

tertiary: gives protein its specific chemical properties

Question 40

what happens if there is a change to the specific shape of a protein?

Answer 40

lose precise structure= usually unable to carry out its biological function

Question 41

what is the role of the rough endoplasmic reticulum in the protein secretory pathway?

Answer 41

- ribosomes attached to the rER allows correct folding of newly formed proteins

Question 42

what is the role of a transport vesicle in the protein secretory pathway?

Answer 42

- contains proteins for transport - transports proteins to the Golgi body - fuses with Golgi membrane - releases protein into lumen | buds of rER

Question 43

what is the role of the Golgi body in the protein secretory pathway?

Answer 43

- modifies proteins (can add or remove chemical groups or proteins) - packages proteins into vesicles for exocytosis

Question 44

what is exocytosis?

Answer 44

type of bulk transport - moves large substances out of a cell

Question 45

what is the role of secretory vesicles?

Answer 45

transport proteins - contains proteins for secretion - pinches off Golgi body - travels through cytoplasm - fuses with plasma membrane - releases proteins into extracellular space