chapter 7- dna structure and gene function

transcription

a cell rewrites a gene's DNA sequence to a complimentary RNA molecule

prion (PrP)

a normal membrane protein that can exist in multiple 3D shapes, at least one of which is abnormal and can cause disease

semi-conservative replication

every new DNA molecule made by a cell is composed of half old and half new DNA

all viruses contain

genetic info and a protein coat

viroid

highly would circle of RNA that lacks a protein coat

synthesis stage of viral replication

host cell produces multiple copies of the viral genome; mutations during this stage are the raw material for viral evolution

why are viruses considered not alive during synthesis?

host cell provides all resources

how would a virus infect a plant cell?

penetrate waxy outer leaf layers and thick cell walls

ribosomes

physical location where translation occurs, contain large and small subunits

introns

portions of the mRNA that are removed before translation

repressor

prevents transcription of genes if binded to a protein

what does the misfiling of prions do?

stimulates others normal proteins to misfold resulting in cell death

genetic code

the set of rules by which a cell uses the codons in RNA to assemble amino acids in a protein

attachment stage of viral replication

virus attaches to a host cell by adhering to a receptor molecule

bacteriophage

virus that infects bacteria

termination 2 of translation

a release factor binds to the stop codon

initiation 2 of translation

a tRNA carrying the first amino acid binds the first codon on the mRNA

elongation 1 of translation

a tRNA carrying the second amino acid binds to the second codon on the mRNA

elongation 4 of translation

a tRNA carrying the third amino acid binds to the third codon

insertion mutation

adds one or more nucleotides to a gene

purines (double ring structure)

adenine and guanine

genome

all of the genetic material in an organism's cell

initiation 1 of translation

an mRNA strand attaches to the small ribosomal subunit

penetration stage of viral replication

animal cells engulf virus (endocytosis), viruses hitch a ride, bacteriophages inject genetic info through cell wall holes

mutation

any change in a cell's DNA sequence

mutagen

any external agent that induces mutations

termination stage of transcription

at the terminator sequence, RNA polymerase detaches from the DNA and releases the RNA strand

what is the correct order of viral replication?

attachment, penetration, synthesis, assembly, release

gene expression

conversion of the information encoded in a gene first into mRNA and then to a protein

where does translation occur?

cytoplasm and ribosome

chromosome

discrete package of DNA coiled around proteins

start codon

AUG (methionine)

operator

DNA sequence located between the promoter and the protein-encoding regions

initiation stage of transcription

RNA polymerase binds to and unzips DNA

elongation stage of transcription

RNA polymerase reads the DNA strand and adds complimentary nucleotides to an RNA strand

lytic infection

an infection by a bacteriophage that causes the host bacterium to burst immediately after assembling new viruses

removing certain introns/ exons

can make nonfunctional proteins

messenger RNA

carries info that specifies a protein

transfer RNA

carry each amino acid to the correct spot along mRNA molecule

silent mutations

change in genetic code that doesn't change the amino acid

epigenetics

changes in gene expression that do not involve changes to the DNA sequence itself

which is the most dense structure of DNA?

chromosomes

operon genes

code specific proteins

ribosomal RNA

combines with proteins to form ribosomes

template strand

contains the DNA sequence that is actually transcribed to RNA

cells controlling gene expression

contributes to different cell types

alleles

encode same RNA or protein products, but may represent different forms

homeotic genes

encode transcription factors that are expressed during the development of an embryo

XX

female

supportive therapy

fluids and other forms of medication to build up a natural immune response (2 weeks)

operon

group of related genes plus a promoter and an operator that control the transcription of the entire group at once

codon

group of three consecutive mRNA bases that corresponds to one amino acid

karyotype

image showing all of an individual organism's chromosomes

lac operon

in E. coli, three lactose-degrading genes plus the promoter and operator that control their transcription

when are lac operons expressed?

in the presence of lactose sugar

post-translational modifications

increase functional outcomes of proteins in an organism

benefit of polysomes

increases and maximizes protein production

lysogenic infection

infection by a bacteriophage where genetic material replicates along with host genome, but infected cells do not immediately produce new viruses; the infection may become lytic at any time

XY

male

characteristics of viruses

much smaller than a cell, lack organelles, nucleus, membrane, cytoplasm, and ribosomes

RNA

multifunctional nucleic acid that differs from DNA

do antibiotics work against viruses?

no

what happens if mRNA is not physically out of the nucleus?

no proteins are produced

frameshift mutation

nucleotides are added or deleted by a number other than a multiple of three

where does transcription occur?

nucleus

release stage of viral replication

once the virus particles are assembled, they are ready to leave the cell

transcription factors

protein that attract RNA polymerase to proper location

promoter

recognized by RNA polymerase, DNA sequence that not only signals a gene's start but also indicates which of the two strands isn the templates

central dogma

relationship between nucleic acids and proteins as a flow of information

deletion mutation

removes nucleotides

splicing

removing intron and connecting externs from pre mRNA to mature mRNA

substitution mutation

replacement of one DNA base with another

gene

segment of DNA that contains instructions to make a specific protein or DNA molecule

complementary

sequence of each strand determines the sequence of the other

polysomes

single mRNA is read multiple times for more proteins

is RNA single or double stranded?

single stranded

virus

small infectious agent that is simply genetic info enclosed in a protein coat

RNA degradation

some mRNA are rapidly destroyed before translation chemically

exons

spliced together to form the mature mRNA that leaves the nucleus to be translated

DNA

store information that each cell needs to produce proteins

assembly stage of viral replication

subunits of protein coat surround the virus's other proteins and the genetic material

double helix

sugar-phosphate backbones, alternating units of deoxyribose and phosphate joined with covalent bonds

protein coat

surrounds the viral genetic material, shape determines form

vaccine

teaches the immune system to recognize one or more molecular components of a virus without actually exposing the person to disease

translation

the information in RNA is used to assemble proteins

initiation 3 of translation

the large ribosomal subunit attaches the small ribosomal subunit

termination 3 of translation

the polypeptide, ribosomal subunits, and remaining tRNA molecules separate

elongation 5 of translation

the process repeats for subsequent codons, tRNAs, and amino acids

elongation 3 of translation

the ribosome moves down one codon on the mRNA, and the first tRNA is released

termination 1 of translation

the ribosome reaches a stop codon

elongation 2 of translation

the second amino acid binds tot he first amino acid with a covalent bond

anticodon

three-base loop that is complementary to one mRNA codon in tRNA

pyrimidines (single ring structure)

thymine, cytosine, uracil

RNA contains _______ instead of thymine

uracil

naked DNA

wrapped around histone proteins