Lecture 3: Transcription and Translation

Question 1

Gene expression

Answer 1

The process by which DNA directs protein synthesis

Question 2

Roles of Proteins

Answer 2

Structural: membranes and organelles
Enzymes: carry out essential reactions
Receptors: proteins that bind to other molecules such as hormones to relay signals inside the cell
Hormones: proteins that are used for the cell to cell communication
Antibodies: destroy foreign materials

Question 3

Central Dogma of Molecular Biology

Answer 3

Concept that cells are governed by a cellular chain of command
DNA -> RNA -> Protein

Question 4

Proteins

Answer 4

Links between genotype and phenotype

Question 5

Transcription

Answer 5

DNA strand serves as a template for the synthesis of a complementary RNA strand

Question 6

Translation

Answer 6

Polypeptide is synthesized using mRNA as a template

Question 7

mRNA (messenger RNA)

Answer 7

Encodes amino acid sequence of a polypeptide

Question 8

tRNA (transfer RNA)

Answer 8

Brings amino acids to ribosomes during translation

Question 9

rRNA (ribosomal RNA)

Answer 9

With ribosomal proteins, makes up the ribosomes, the organelles that translate the mRNA

Question 10

snRNA (small nuclear RNA)

Answer 10

With proteins forms complexes that are used in RNA processing in eukaryotes

Question 11

RNA Polymerase

Answer 11

Separates the DNA strands and joins the RNA nucleotides together as they base-pair with the DNA template

Question 12

Promoters

Answer 12

Are the specific sequence of DNA in a gene where transcription is initiated

Question 13

Poly (A) Tail

Answer 13

Consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases

Question 14

Polyadenylation

Answer 14

In eukaryotes part of the process that produces mature messenger RNA (mRNA) for translation

Question 15

Splicosome

Answer 15

Complex of small RNAs

Question 16

Alternative RNA Splicing

Answer 16

• Genes that can encode more than one kind of polypeptide depending on which segments are treated as exons during pre-mRNA splicing
• Alternative splicing increases the number of different proteins an organism can produce is greater than genes

Question 17

Non-Coding RNA

Answer 17

Are a variety of small RNAs that perform diverse regulatory roles such as ribozymes, microRNAs, etc. Before it was assumed that most DNA that doesn’t code for proteins, rRNA, or tRNA was transcribed.

Question 18

Codons

Answer 18

• Triplets of nucleotide bases that code for an amino acid. Codons are read in the correct reading frame (starting with AUG) in order for the specified polypeptide to be produced.
• 64 codons 4^3: 61 code for amino acids and 3 are stop codons
• AUG (Met) is the start codon

Question 19

Transfer RNA (tRNA)

Answer 19

• each transfer RNA is specific for one amino acid and for a particular codon in mRNA
• anticodon in the tRNA is complementary to the mRNA codon
• anticodon determines which amino acid is attached to the tRNA
• family of tRNA molecules enables the codons in a mRNA molecule to be translated into the sequence of amino acids in the protein

Question 20

Anticodon

Answer 20

Complementary to the mRNA codon

Question 21

Wobble

Answer 21

Flexible pairing at the third based of a codon that allows some tRNAs to bind to more than one codon

Question 22

Shine-Dalgarno Sequence

Answer 22

Ribosomal binding site in bacterial and archaeal messenger RNA, generally located around 8 bases upstream of the start codon AUG

Question 23

Ribosomes

Answer 23

• This is where translation occurs, it consists of two subunits- a large and a small that are both made of proteins and ribosomal RNA (rRNA)
• They facilitate specific coupling of tRNA anticodons with mRNA codons during protein synthesis
• Ribosomes have a binding site for mRNA and three binding sites for tRNA

Question 24

P Site (peptidyl-tRNA site)

Answer 24

Is the binding site of initiator tRNA-Met and holds the tRNA carrying the growing polypeptide chain

Question 25

A Site (aminoacyl-tRNA site)

Answer 25

Holds the tRNA with the next amino acid to be added to the chain

Question 26

E Site (exit)

Answer 26

Is where empty (uncharged) tRNAs leave the ribosome

Question 27

Non-Coding RNA

Answer 27

Are a variety of small RNAs that perform diverse regulatory roles such as ribozymes, microRNAs, etc. Before it was assumed that most DNA that does n;t code for proteins, rRNA, or tRNA were transcribed.