Chapter 7 DNA structure & gene function Flashcards
What is DNA made up of?
(DNA is a double helix made up of nucleotides.)
Phosphate group, sugar (deoxyribose) and a nitrogenous base (adenine, thymine, guanine, and cytosine.)
What is DNAs function?
DNA stores the information that a cell needs to produce proteins.
Which nitrogenous bases are double ring structures and which are single ring? And what are those called?
Adenine and guanine are double ring (purines)
Thymine and cytosine are single ring (pyrimidine)
What type of bonds Connect complementary DNA strands?
Hydrogen bonds
What are the complementary base pairing’s?
Adenine binds to thymine
Guanine binds to cytosine
What is genome?
All of the genetic material in it cells
What are chromosomes?
Long DNA molecules that associate closely with proteins
What is a Gene?
Sequence of DNA nucleotides that code for specific protein or RNA molecule (blueprint)
What is the central dogma of biology?
DNA to RNA (transcription) to protein (translation)
What are the two stages of protein production?
Transcription and translation
What are the three types of RNA? And their functions?
mRNA-carries the info that specifies a
Protein
rRNA-forms part of a ribosome in the nucleolus
tRNA-connector that binds mRNA codon at one end and corresponding amino acid at the other. Transfers amino acids available one by one to ribosome.
What is the complementary RNA bases to DNA?
Adenine to Uracil
Cytosine to guanine
Guanine to cytosine
Thymine to adenine
Where does transcription occur?
In the nucleus
What are the three stages of transcription?
Initiation, elongation, and termination.
What happens in initiation for transcription?
RNA polymerase binds to the promoter, enzymes unzip the DNA, the DNA template strand encodes the RNA molecule.
What happens in elongation of transcription?
RNA polymerase moves along template strand making an RNA copy. RNA molecule is complementary to the DNA template strand.
What happens in termination for transcription?
RNA polymerase reaches the terminator, RNA DNA and RNA polymerase separate, DNA becomes a double helix again.
What happens with Intron’s and exons?
Intron’s are spliced out of the RNA molecule before exiting the nucleus. Exons are spliced together and exit the nucleus for translation.
What occurs after termination in transcription, before the mRNA exits the nucleus?
Poly A tail and mRNA CAP Are added to the mRNA. Intron’s are spliced out.
What are the three steps of translation?
Initiation elongation and termination.
What result occurs in translation as an end result?
The construction of a protein
What is a codon?
Three nucleotide sequence (One amino acid).
Where does translation occur in the cell?
At the ribosomes in the cytoplasm
What happens in initiation of translation?
Small ribosomal subunit binds to mRNA, large ribosomal subunit then Binds. First tRNA molecule binds to the start codon, tRNA complementary base pairs to mRNA. tRNA
carries corresponding amino acid.
What occurs in elongation of translation?
Amino acids covalently bond, the first tRNA leaves, the Ribosome moves to the right and a third tRNA comes in. this process continues as the protein grows.(linear polypeptide bond)
What is located at each end of a tRNA molecule?
Amino acid & anticodon
Where must an mRNA attach before protein production can begin?
Smaller ribosome
How does mRNA exit the nucleus?
Nuclear pores
What type of bond is formed between amino acids?
Peptide (covalent)
Translate from DNA to RNA
TAC CTC CGG TGG GTG CTT GTC TGT ATC
AUG GAG GCC ACC CAC GAA CAG ACA UAG
What happens in termination of translation?
The ribosome reaches the stop codon (AUU, UAG, UGA).The polypeptide detaches, chaperone proteins stabilize & carry the protein to be properly folded.
Multiple ribosomes can translate the same mRNA and begin protein building.
True
What are the three methods used in the nucleus for gene regulation?
DNA availability, transcription factors, and splicing (Intron’s)
What are the three methods used in the cytoplasm to regulate gene expression?
MRNA leaving the nucleus, mRNA degradation, and protein processing degradation.
Why do cells regulate which genes are expressed at any given time?
To save energy
What is mutation?
A change in a cell’s DNA sequence
What is point mutation?
Changes in one or a few base pairs in a gene
Name the five types of point mutations.
Wild type substitution frameshift deletion insertion
Explain wild type mutation.
The original nucleotide sequence
Explain substitution mutation.
The replacement of one DNA base with another. (The most common genotype, phenotype or Allele.)
Explain frameshift mutation.
Nucleotides are added or deleted by a number other than a multiple of three. Disrupts the entire reading frame or sequence of amino acids (devastating).
Explain deletion mutation.
Nucleotides deleted
Explain insertion mutation.
Nucleotides added
What causes mutations?
Spontaneous or mutagens
What is spontaneous mutation?
Mutations caused without outside causes.
What is mutagen Mutations?
External agent that induces mutations
Give 4 facts about mutations.
- Mutations are not always harmful.
- mutations create alleles.
- genetic variation is important for evolution.
- plant breeders induce mutations to create new varieties.
What is the job of chaperone proteins?
Stabilize partially folded regions of a new protein
What is the start codon and three stop codons?
START: AUG
STOP: UGA, UAA, UAG
In termination of translation what binds to the stop codon?
Release factors
In initiation of translation, the tRNA already carries what?
Methionine (start amino acid, AUG)
In gene regulation DNA availability does what?
Unneeded DNA is tagged. Proteins in the cell signal cell to fold DNA too tight for RNA polymerase to access deeming it inactive.
What helps RNA polymerase bind to the promoter in transcription?
Transcription factors
The gene regulation mRNA processing includes what?
Intron’s being removed
