2.4 - How is the CFTR protein made? Flashcards
What is a gene?
A sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain.
What is a genome?
All of the genes in an individual or species is called a genome
What is DNA?
One type of nucleic acid, called deoxyribonucleic acid. It is made of many units of nucleotides.
What are chromosomes?
Chromosomes contain large amounts of DNA and carry many genes.
How are Nucleotides made and what are the bonds formed called?
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
Where does transcription take place?
The nucleus
What bases pair up with each other?
T , A
G, C
What is a Triplet code?
Groups of three bases code for an amino acid
What does non overlapping mean?
Each DNA triplet code is adjacent
Why does the DNA never leave the nuclues?
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.
What are the differences between RNA and DNA?
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
What is a condon?
Three mRNA bases that code for an amino acid
What is mRNA?
A single stranded nucleic acid
What is uracil?
The base that replaces thymine in RNA
What is RNA polymerase?
The enzyme that causes the DNA strand to unwind in transcription
What is a template strand?
The DNA strand that mRNA attaches to in transcription
What is a coding strand?
The DNA strand that mRNA makes a copy of in transcription
What is the process of transcription?
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’.
How is RNA transfered?
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.
What are ribsomes?
Ribosomes are small organelles made of ribosomal RNA and proteins.
Ribosomes can float freely or be attached to endoplasmic reticulum (ER) an organelle.
Where does translation take place?
On the ribsomes
What 2 things are tRNA made up of?
RNA and a specific amino acid
What is an anticodon?
3 bases found on tRNA
The process of translation?
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
What is the role of ribsomes?
The ribosome holds the mRNA, tRNA, amino acids and associated enzymes in place.
Role of making a peptide bond?
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.
When does the polypeptide chain stop growing?
When a a stop codon is exposed on the ribosome
What are 3 stop condons?
UAA, UAC or UGA.
