2.4 - How is the CFTR protein made?

Question 1

What is a gene?

Answer 1

A sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain.

Question 2

What is a genome?

Answer 2

All of the genes in an individual or species is called a genome

Question 3

What is DNA?

Answer 3

One type of nucleic acid, called deoxyribonucleic acid. It is made of many units of nucleotides.

Question 4

What are chromosomes?

Answer 4

Chromosomes contain large amounts of DNA and carry many genes.

Question 5

How are Nucleotides made and what are the bonds formed called?

Answer 5

Mononucleotides join together by condensation reactions to form a polynucleotide
The bonds form between the sugar of one nucleotide and the phosphate of the next nucleotide.
The bond is called a phosphodiester bond

Question 6

Where does transcription take place?

Answer 6

The nucleus

Question 7

What bases pair up with each other?

Answer 7

T , A

G, C

Question 8

What is a Triplet code?

Answer 8

Groups of three bases code for an amino acid

Question 9

What does non overlapping mean?

Answer 9

Each DNA triplet code is adjacent

Question 10

Why does the DNA never leave the nuclues?

Answer 10

DNA stays in the nucleus
The DNA is copied into mRNA (transcription) in the nucleus.
The mRNA is a single strand polynucleotide made of ribonucleic acid.
The mRNA leaves the nucleus through pores in the nucleus.

Question 11

What are the differences between RNA and DNA?

Answer 11

RNA DNA
bases - ACGU ATCG
complementry base paring complementry base paring
A with U A with T
C with G C with G
Ribose sugar deoxyribose sugar
Single strand double strand

Question 12

What is a condon?

Answer 12

Three mRNA bases that code for an amino acid

Question 13

What is mRNA?

Answer 13

A single stranded nucleic acid

Question 14

What is uracil?

Answer 14

The base that replaces thymine in RNA

Question 15

What is RNA polymerase?

Answer 15

The enzyme that causes the DNA strand to unwind in transcription

Question 16

What is a template strand?

Answer 16

The DNA strand that mRNA attaches to in transcription

Question 17

What is a coding strand?

Answer 17

The DNA strand that mRNA makes a copy of in transcription

Question 18

What is the process of transcription?

Answer 18

1- RNA polymerase enzyme attaches to the DNA and the gene being transcribed unwinds.
2- The hydrogen bonds break between bases.
3-The sequence on one strand (the template strand) is transcribed to make an mRNA molecule with the same sequence as the DNA coding strand.
4- Free RNA nucleotides in nucleus pair up with its complementary DNA base and attaches to the DNA. Phosphodiester bonds form between the RNA nucleotides.
5- This produces a single stranded molecule of mRNA.
6- mRNA detaches from the DNA and leaves the nucleus through a pore in the nuclear envelope. The DNA molecule ‘zips up’.

Question 19

How is RNA transfered?

Answer 19

Amino acids float freely in cytoplasm and then bind one end of the tRNA
Anticodons matche up with a specific complementary codon on the mRNA.
Each amino acid has its own specific tRNA molecule.

Question 20

What are ribsomes?

Answer 20

Ribosomes are small organelles made of ribosomal RNA and proteins.
Ribosomes can float freely or be attached to endoplasmic reticulum (ER) an organelle.

Question 21

Where does translation take place?

Answer 21

On the ribsomes

Question 22

What 2 things are tRNA made up of?

Answer 22

RNA and a specific amino acid

Question 23

What is an anticodon?

Answer 23

3 bases found on tRNA

Question 24

The process of translation?

Answer 24

1- The mRNA leaves the nucleus and attaches to a small ribosome subunit where it is held so that the tRNA can line up.
2- The ribosomes expose 6 bases of the mRNA at a time.
3- tRNA binds to the ribosome on the larger subunit opposite to where the mRNA has bound.
4- The first codon exposed is always AUG. This is the start codon.
5- The tRNA with the complementary anticodon UAC will pair up, bringing its attached amino acid (methionine) with it.
6- The next codon on the mRNA will pair up with its complementary anticodon on the tRNA

Question 25

What is the role of ribsomes?

Answer 25

The ribosome holds the mRNA, tRNA, amino acids and associated enzymes in place.

Question 26

Role of making a peptide bond?

Answer 26

The peptide bond forms in a condensation reaction between
the amine group of one amino acid and the carboxylic acid group
of the next, forming a dipeptide.

Question 27

When does the polypeptide chain stop growing?

Answer 27

When a a stop codon is exposed on the ribosome

Question 28

What are 3 stop condons?

Answer 28

UAA, UAC or UGA.