Chapter 25 Flashcards
What is DNA a chain of?
Nucleotides.
What do all nucleotides have?
Phosphate group, deoxyribose sugar, nitrogen base.
What are the purine bases?
Guanine and Adenine.
How many rings do purine bases have?
2.
What do pyrimidines have?
A single ring nitrogenous base.
What are the single ring nitrogenous bases?
Cytosine and Thymine.
Describe the backbone of a strand.
One nucleotide connect to the other by phosphate groups. Sticking out of the sugar group is a nitrogenous base.
What bases bond together?
Adenine and thymine, cytosine and guanine.
How do the bases bond together?
Hydrogen bonds.
What is the corresponding strand to CGGTACATG?
GCCATGTAC.
Describe the 2 strands.
Anti parallel, many thousands of nucleotides in length, form a double helix structure.
What is helicase?
The enzyme that unzips double stranded DNA.
What is polymerase?
An enzyme that fits complementary DNA nucleotides to complimentary bases on loose single strands.
What is DNA replication?
The process of copying one DNA double helix into two identical double helices.
What is DNA ligase?
Enzyme that seals any breaks in sugar phosphate backbones and ensure two new double helix molecules are identical to original.
What does each daughter DNA molecule consist of?
One new chain of nucleotides and one from the parent DNA molecule.
Will the two daughter DNA molecules be identical to the parent molecule?
Yes.
What is RNA?
A single stranded molecule that has 3 of the same nucleotides as DNA. (Adenine, guanine, and cytosine) but has Uracil instead of thymine.
What does RNA do?
Help DNA produce proteins.
Describe mRNA.
(Messenger RNA), produced in the nucleus, a section of DNA serves as a template to create a particular mRNA. Call this transcription.
What does RNA polymerase do?
Binds to a special sequence of DNA nucleotides in double helix.
What is the special sequence of DNA called?
A promoter.
What do RNA polymerase and the promoter do?
Cause a section of DNA double helix to open.
After opening the double helix of DNA what does RNA polymerase do?
Helps with complementary pairing of the RNA nucleotides to the DNA nucleotides.
What is an intron?
Intragene segments that will be cut off/eliminated. Parts that wont become ultimate mRNA.
What is an exon?
RNA nucleotides that remain and will be expressed. It is necessary to splice the exon parts together after introns are removed.
Describe the structure of the mRNA.
Cap at one end, Poly A tail at the other.
Describe tRNA.
Produced in the nucleus from DNA. 3 of the nucleotides are the anticodon. Specific tRNA types link with a specific amino acid.
What do tRNA’s do with the amino acids?
Bring them to ribosomes to make proteins.
Describe rRNA.
Produced in the nucleolus of nucleus, use section of DNA located there to make a strand. Goes to the cytoplasm and combines with proteins and other rRNA molecules.
What makes a ribosome?
Many proteins and several rRNA strands combination.
What is the structure of a ribosome?
Large and small subunit.
What does the combination of rRNA and proteins provide for ribosome?
A site for mRNA to go and conduct protein synthesis.
How does mRNA feed through the ribosome?
A channel. It also makes it possible for mRNA and tRNA to meet.
Briefly, what is translation?
When the mRNA is read by every 3 nucleotides when going through ribosome.
What does the sequence of nucleotides on mRNA determine?
Amino acid sequence.
What is a codon?
The triplet code.
What is initiation?
When translation components come together.
What is always the first codon on mRNA?
AUG.
What does the first tRNA bind to?
Large subunit of ribosome.
What happens after first binding of tRNA?
Second tRNA comes with its matching anticodon and associated amino acid.
What does the start amino acid do?
Makes a peptide bond with second amino acid.
Why does a peptide bond occur during protein synthesis?
Because large subunit is a catalytic site.
What happens after peptide bond formation between 2 amino acids?
First, tRNA now released, mRNA moves forward… next codon of mRNA waits to match corresponding anticodon of tRNA and associated amino acid.
3rd part of protein synthesis?
Peptide bond between 2nd and 3rd amino acid. tRNA of 2nd amino acid released and mRNA moves forward. Creates a peptide chain or protein and process continues until a stop codon is reached.
What does elongation have to do with?
The process of building up polypeptide chain one amino acid at a time.
What happens after stop codon?
Peptide chain is released into cytoplasm.
What happens after protein synthesis is over?
Polypeptide goes off and assumes 3D shape in cytoplasm and mRNA is released. Ribosomal subunits then disassociate.
What is a gene mutation?
A permanent change in the sequence of bases in DNA. The effect can range from none to complete inactivity of the protein.
What can mutations lead to?
Cancer.
What are mutagens?
Environmental influences that can cause mutations.
What is a transposon?
Jumping genes; specific DNA sequences that move within and between chromosomes.
What are point mutations?
Involve a change in a single DNA nucleotide.
What are possible outcomes of point mutations?
May cause change in specific amino acid,
May have no effect at all
May produce an abnormal and/or incomplete protein.
What is a frameshift mutation?
One or more nucleotides are either inserted or deleted from DNA.
What are some outcomes of a frameshift mutation?
Cause a premature stop codon
Result in a non-sense codon sequence
It becomes an incomplete/non-functional protein.
Describe characteristics of cancer cells.
Cancer cells are genetically unstable.
