chapter 2b

Question 1

anti parallel meaning

Answer 1

Running in an opposite direction to the other (still parallel)

Question 2

whats complementary base pairing

Answer 2

describes which nucleotides can form hydrogen bonds with each other C/G and A/T (U in RNA).

Question 3

whats messenger RNA (mRNA)

Answer 3

RNA molecules that are produced during transcription and carry genetic information from the nucleus to the ribosomes.

Question 4

whats transfer RNA (tRNA)

Answer 4

RNA that recognises specific codons on the mRNA strand and adds the corresponding amino acid to the polypeptide chain during protein synthesis.

Question 5

whats ribosomal RNA (rRNA)

Answer 5

RNA that is a key structural component of ribosomes, which assembles proteins.

Question 6

whats transcription

Answer 6

The process whereby a sequence of DNA is used as a template to produce a complementary sequence of mRNA

Question 7

whats translation

Answer 7

The process where an mRNA sequence is read to produce a corresponding amino acid sequence to build a polypeptide

Question 8

whats a triplet

Answer 8

The sequence of three nucleotides in DNA coding for one amino acid.

Question 9

whats a codon

Answer 9

The sequence of three nucleotides in mRNA coding for one amino acid.

Question 10

whats a promoter

Answer 10

The sequence of DNA to which RNA polymerase binds. (e.g. TATA box – promoter region)

Question 11

whats an RNA polymerase

Answer 11

The enzyme responsible for constructing a pre-mRNA sequence from a DNA sequence during transcription.

Question 12

whats an intron

Answer 12

Non-coding regions of DNA that do not code for proteins. They are spliced out during RNA processing

Question 13

whats an exon

Answer 13

Regions of DNA that code from proteins and are not spliced out during RNA processing

Question 14

whats a termination sequence

Answer 14

A sequence of DNA that signals the end of transcription.

Question 15

whats an operator

Answer 15

A short region of DNA that interacts with repressor proteins to alter the transcription of an operon.

Question 16

whats an operon

Answer 16

The gene/genes that get transcribed when the operator is bound.

Question 17

whats a repressor protein

Answer 17

a protein coded for by a regulatory gene that prevents gene expression by binding to its operator

Question 18

what makes up the DNA structure

Answer 18

DNA is made up of two polynucleotide chains which run antiparallel to each other. We call the first strand as running from 5’ to 3’ (phosphate and O pointing up) and the other is running 3’ to 5’ (phosphate and O pointing down).
The nucleotides from each chain forms a hydrogen bond with one another. Cytosine (C) forms three hydrogen bonds with Guanine (G), and Adenine (A) forms two hydrogen bonds with Thymine (T) in DNA and Uracil (U) in RNA. This forms a complementary base pairing as they can only bond with their complementary base pair.
Due to this, we can predict the number of nucleotides as there will always be an equal amount of A to T/U and C to G.
DNA forms a double helix which coils around histone proteins. These histone proteins condense even further to form chromosomes.

Question 19

three types of RNA structures

Answer 19

mRNA: Carries genetic information from nucleus to protein for protein synthesis.
tRNA: delivers specific amino acids to the ribosomes.
rRNA: serves as the structural component of ribosomes within cells.

Question 20

why is Uracil used in RNA instead of Thymine

Answer 20

Thymine is used with DNA, but Uracil is used with RNA.
This is due to T reacting with oxygen outside of the nucleus, causing it to degenerate faster than normal. Therefore, we replace T with U to ensure longevity of the DNA sequence as it travels outside of the nucleus to the ribosomes.