Chapter 8 Flashcards
Define genetics
The study of genes, how they carry information, how information is expressed, and how genes are replicated
Define Chromosomes
Structures containing DNA that physically carry herediary information; the chromosomes contain genes
Define Genes
Segments of DNA that encode functional products, usually proteins
Define Genome
All the genetic information in a cell
What is the genetic code?
A set of rules that dtermines how a nucleotide sequence is converted to an amino acid sequence of a protein
Define genotype
The genetic makeup of an organism
Phenotype
Expression of the genes (hair color, eye color, etc)
Vertical gene transfer
Flow of genetic information from one generation to the next
DNA forms a ____ ______
Double helix
What does the “backbone” of DNA consist of?
Deoxyribose-phosphate
Fill in the blanks
DNA Replication
- “Backbone” consists of _____-______
- Twostrands of nucleotides are held together by hydrogen bonds between ____ and _____
- Strands are ________ in arrangement
- Order of the ___________ bases forms the _______ ____ of the organisms
- deoxyribose-phosphate
- A-T and C-G
- Antiparrallel
- nitrogen-containing; genetic instructions
How many strands serve as the template for the production of a second strand?
1
Topoisomerase and gyrase - they ____ and ____ the strands
twist; relax
_______ separates the DNA strands during DNA replications
Helicase
During DNA replication what makes a molecule of DNA? How does it do this?
DNA polymerase;
It adds nucleotides to the growing DNA strand
Which direction does DNA polymerase go?
5’-3’ direction
The process of DNA ploymerase adding nucleotides to the growing DNA strand is initiated by a_______ _____.
The leading strand is synthesized _______ while the lagging strand is synthezised ________, creating ___________ ______
RNA primer
continually
discontinually
okazaki strands
Towards end of DNA replication DNA polymerase removes ____ ____; ____ ___ are joined by _____ ____ and ____ _______
RNA primers
Okazaki fragments
DNA polymerase and DNA ligase
Energy for DNA replication is supplied by _____.
_____ of two phopshate groups on _____ provides energy
Nucleotides
Hydrolysis; ATP
DNA replication is ________ which means what?
Semiconservative; This means each new double stranded DNA molecule contains one original strand and one new strand
Most bacterial DNA replication is ________
Bidirectional
How many copies of the DNA molecule can each offpsring of DNA replication receive?
One
Is DNA replication accurate? If so, why?
Yes because of the proofreading capabilities of the DNA polymerase.
What three things do you know about Ribonucleic acid?
- Single-stranded nucleotide
- 5-carbon ribose sugar
- Contains uracil (U) insteadof thymine (T)
What is the integral part of ribosomes?
Ribosomal RNA (rRNA)
What transports amino acids during protein synthesis?
Transfer RNA (tRNA)
What carries coded information from DNA to ribosomes?
Messenger RNA (mRNA)
Transcription proceeds in the ___ -> ___ direction.
It stops when it reaches the ____ sequence on DNA.
Transcription begins when ___ _____ binds to the _____ sequence on DNA.
What is synthesized during transcription in prokaryotes?
- 5 3
- terminator
- RNA polymerase ; promoter
- Sntehsis of a complementary mRNA strand from a DNA template
mRNA is translated into the _______ of proteins
“language”
Codons
Groups of three mRNA nucleotides that code for a particular amino acid
___ ___ ____ encode 20 amino acids
61 sense codons
Degeneracy
Genetic code involves degeneracy - each amino acid is coded by several codons (translation)
What is the start codn? What does this do?
AUG; translation of mRNA begins at the start codon
3 nonsense codons
UAA, UAG, UGA
Codons of rRNA are ____ sequentially
“read”
tRNA molecules transport the required ____ ___ to the ribosome
tRNA molecules also have a ______ that base-pairs with the codon
Amino acids are joined by _____ ____
- amino acids
- anticodon
- peptide bonds
In bacteria, translation can beginn _____ transcription is complete.
before
Mutation
A permanent change in the base sequence of DNA
Mutations may be _______, ____, or ____
Mutual, beneficial, harmful
Mutagens
Agents that cause mutations
Spontaneous mutations
Occur in the absence of a mutagen
Base substitution
(point mutation)
Change in one base in DNA
Missense mutation
Base substitution results in change in an amino acid
Base substitution results in a nonsense (stop) codon
Nonsense mutation
Base substitution results in change in an amino acid
Missense mutation
Change in one base in DNA
Base substitution
Insertion or deletion of one or more nucleotide pairs
Shifts the translational “reading frame”
Framshift mutation
Causes adenine to bind with cytosine instead of thymine
Nitrous acid
Incorporates into DNA in place of a normal base; causes mistakes in base pairing
Nucleosid analog
Causes the formation of ions that can ozidize nucleotides and break the deoxyribose-phosphate backbone
Ionizing radiation
Causes thymine dimers
UV radiation
Separate thymine dimers
Light repair-photolyases
Enzymes cut out incorrect bases and fill in corect bases
Nucleotide excision repair
Detects mutant cells because they grow or appear idifference than unmutated cells
Positive (direct) selection
Detects mutant cells that cannot grow or perform a certain function
Negative (indirect) selection
Mutant that has a nutritional requirement absent in the parent
Auxtotroph
Use of replica plating
Test that exposes mutant bacteria to mutagenic substances to measure the rate of reversal of themutation
What does it indicate?
Ames test
Degree to which a substance is mutagenic
