Flashcards in Test 2 Deck (47):
DNA stores the information that a cell needs to produce what?
Where is DNA located?
In the nucleus
All genetic material in a cell
Long molecules that carry the information needed to make proteins
Specific sequences in DNA that codes for a specific protein
DNA has a specific structure known as what?
A double helix
The nucleotide structure of DNA contains what 4 components?
Adenine, Thymine, Guanine, and Cytosine
What are the strands of DNA doing that allows them to bond?
The phosphate groups on the left side point upward while the ones on the right point down. This anti-parallelism allows the bonds to be made.
What bonds hold the nucleotides together, much like protein bonds?
What are the three types of RNA?
Messenger RNA, Transfer RNA, and Ribosomal RNA
What does transcription do?
Produces an RNA copy of DNA, the short-hand version of it.
What happens in the stage initiation of transcription?
An enzyme (Gyrase) unwinds DNA from its super coil. Then, another enzyme (Helicase) unzips the DNA by breaking the hydrogen bonds. Further along is another enzyme (RNA Polymerase) that puts down the matching nucleotides to help build RNA.
How do enzymes know where to bind?
There is a section that tells the enzymes where to bind, the promoter.
What is the relationship between a gene and a protein?
A gene codes for a specific protein. Genes are located on chromosomes.
What are the three stages of transcription and translation?
Initiation, elongation, and termination
What happens during elongation in transcription?
An RNA molecule that is complimentary to the DNA strand comes to match nucleotides to the DNA, creating an mRNA. Eventually, you get a full copy of a gene.
What happens to the mRNA before it leaves the nucleus to begin translation in the cytoplasm?
The non-coding introns are taken out, or spliced out. A G-cap is added to one end while a line of adenine known as the Poly-A tail is added to the other.
What does the Poly-A tail allow an mRNA to do?
It protects from enzymes breaking down the mRNA and allows the mRNA to be messed with many times.
Where does translation occur?
At ribosomes in the cytoplasm
What is a three-nucleotide sequence that encodes one amino acid?
Name the 4 specific codons and their functions.
AUG - Methionine (MET) which is the starting codon.
The three stopping codons are UAA, UAG, and UGA.
What happened in translation's initiaion phase?
A small ribosomal subunit looks for the MET. mRNA is met with tRNA.
What happenes during the elongation process in translation?
mRNA and tRNA continue to be paired, creative polypeptides with all the amino acids being bonded together. Eventually, you hit a stop codon with a release factor protein telling everything to let go and stop translating.
Translation is efficient when what happens?
Multiple ribosomes attach to an mRNA molecule simultaneously.
Cells save energy by producing only what?
What control gene expression in the chromosomes of prokaryotes?
The promoter and operator
How do bacteria regulate genes?
Using a repressor
Bacterial genes are grouped together in a group called what?
Why do cells regulate which genes are expressed at any given time?
Expression based on need and are regulated to save energy.
Any change in a cell's DNA sequence
Types of mutations
Substitution and frame-shift (deletion and insertion)
Mutations vary how
Insignificant, negative, lethal, and positive
Mutations occur due to external agents known as
If the substitution triggers an amino acid change, it is called a ______ mutation.
If the substitution leads to a premature stop codon, it is called a ______ mutation.
How can mutations be good?
Mutations can create new alleles, different versions of genes, which leads to diversity and helps with natural selection. Geneticists and breeders use mutations to study genes, disease, and modification of genes.
Makes genetically identical daughter cells.
Production of gametes
Meeting of gametes
Fertilized egg, first cell after fertilization
What precedes cell division?
In mitosis, each double-stranded DNA molecule consists of one parental and one daughter strand as a result of ______.
The DNA in the cell is loose in the nucleus so DNA replication can occur.
The DNA in the cell is condensed into a visible chromosome
Groups of histone proteins that take general from of chromosome
Wraps of nuclesomes
Before cell division, nuclesomes cluster together into _____.