protein synthesis

Question 1

enzymes

Answer 1

• most important class of proteins
• help speed up necessary biochemical reactions that take place inside the cell

Question 2

proteins

Answer 2

• nearly every cellular process involves proteins
• proteins are polymers (or chains) of many amino acid building blocks

Question 3

proteome

Answer 3

a cells full complement of proteins

Question 4

gene

Answer 4

• functional segment of DNA that provides the code necessary to construct a particular protein
• each gene provides the code necessary to construct a particular protein
• sequence of bases in a gene (A-T, C-G nucleotides translates to an amino acid sequence

Question 5

gene expression

Answer 5

transforms information coded in gene into a final gene product
- dictates the structure and function of a cell by determining which proteins are made

Question 6

triplet

Answer 6

section of 3 dna bases in a row that codes for a specific amino acid
ex: CAC – amino acid valine
- gene composed of multiple triplets in sequenecs provides code to build whole protein

Question 7

mRNA

Answer 7

• single-stranded nucleic acid that carries a copy of the genetic code for a single gene out of the nucleus into the cytoplasm (there used to produce proteins)

Question 8

how is dna and rna different?

Answer 8

• rna is single stranded and has no complementary strand
• ribose sugar in rna has additional oxygen atom
• rna has uracil instead of thymine (A-U)

Question 9

transcription

Answer 9

• synthesis of a strand of mrna that is complementary to the gene of interest
• mrna is like a ‘transcript’ or copy of dna code
  1.starts with region of dna unwinds and 2 strands seperate
  2.triplets within gene on section of dna used as template to transcribe complementary strand of rna
  3. codons (3 base sequence of mrna) encode to amino acidsw

Question 10

what are the 3 stages of transcription

Answer 10

1. initiation: region at begining of gene called a promoter (specific sequence of nucleotides) triggers the start of transcription
2. elongation: rna polymerase unwinds dna segment, coding strand becomes template, polymerase aligns correct nucleic acid (ACGU) with its complementary base on coding strand of dna
3. termination: end of gene a sequence of nucleotides called the terminator causes new rna to folw up on itself

Question 11

what is rna polymerase

Answer 11

enqyme that adds new nucleotides to a growing strand of rna

Question 12

what happens to pre mrna before it leaves nucleus

Answer 12

• ## splicing: removes noncoding regions from pre-mrna transcript

Question 13

what is a spliceosome

Answer 13

structure made of various protions that attatches to mrna and splices or cuts of noncoding regions

Question 14

intron

Answer 14

• removed segment of transcript

Question 15

exon

Answer 15

segment of rna that remains after splicing
- pasted together afterwards

Question 16

translation

Answer 16

process of synthesizing a chain of amino acids called a polypeptide

Question 17

polypeptide

Answer 17

chain of amino acids

Question 18

what two major aids does translation require?

Answer 18

• ‘translator’ molecule that conducts the translation
• a substrate on which the mrna strand is translated into a new protein (like a translators desk)

both fulfilled by rna!

Question 19

ribosomal rna (rrna)

Answer 19

• composes the structure of ribosome (with proteins)

Question 20

transfer rna (trna)

Answer 20

• translator molecule physically ‘read’ the mrna codons
• type of na that ferries the approprate correstponding amino acids to the ribosome and attaches each new amino acids to the ribosome
• also attaches each new amino acid to the last, building the polypeptide chain one-by-one
• trna molcules transfer specific amino acids from cytoplasm to growing polypeptides
• must be able to recognize codons on mrna and match them with the right amino acid

Question 21

trna structure

Answer 21

• one end is a binding site for a specific amino acid
• other end is a base sequence of 3 bases on the trna (called an anticodon)

Question 22

processes of translation

Answer 22

1. initiation: takes place when binding of ribosome to mrna transcript
2. elongation: recognition of a trna anticodon with next mrna codon in the sequence
   - trna releases mrna strand
   - mrna shifts one codon over in ribosome
   - next appropriate trna arrives with matching anticodon
3. termination: process continues until final codon on mrna is reached and provides a ‘stop’ message that signals termination of translation and triggers the release of the complete newly synthesized protein
   - a gene within the dna molecules in transcribed into mrna and its translated into protein product

Question 23

polyribosome

Answer 23

string of ribosomes translating a single mrna strand