Chapter 12B: DNA and RNA - QUIZ

how is genetic code read?

3 letters at a time

what does each tRNA carry?

ONE kind of amino acid, it contains an anticodon that is complementary to the codon being read at the ribosome

what does the enhancer act as a magnent for?

RNA polymerase

what is each 3-base sequence called?

a codon

what is an operon?

a group of genes that operate together

what kind of bonds does the ribosome form?

a peptide bond between the 1st and 2nd amino acid and breaks the 1st amino acid from its tRNA and making room for another codon to be read

what are the 2 regulatory regions on the side of the operon?

a promotor (P) which begins transcription and the operator (O)

what does each codon code for?

a specific amino acid

what does a typical gene have?

a start signal for transcription, a stop signal for transcription, a promoter (RNA polymerase binding sight), regulatory sites, and the nucleotide sequence that is transcribed

what is a nonsense mutation?

a stop codon is introduced producing a truncated protein

Which types of RNA are involved in protein synthesis?

all 3, mRNA, tRNA, and rRNA

how do many proteins function?

as enzymes or structures, able to produce the characteristics of organisms (such as color, size, shape, etc.)

what is an insertion?

base inserted into the DNA sequence, can have a dramatic effect because it causes the codon groupings to shift, therefore coding for entirely different amino acids

what is an enhancer sequence?

can regulate genes because proteins can bind here; some proteins open up tightly packed chromatin, others attract RNA polymerase, others block access to genes, etc

what is messenger RNA?

carries copies of the instructions (from DNA) for the assembly of amino acids into proteins

what does gene regulation in eukaryotes allow for?

cell specialization

what is a gene?

coded DNA instructions that control the production of proteins within the cell

what is translation?

decoding of an mRNA molecule into a polypeptide chain

which is more complex - gene regulation in eukaryotes or prokaryotes?

eukaryotes

what is an example of a gene encoded protein?

eye color

what is ribosomal RNA?

forma part of ribosomes, where proteins are assembled

what is an expressed gene?

gene that is transcribed into RNA; only a fraction of the genes in a cell are expressed at any given time. if a specific kind of protein is not continually used by a cell, the gene for that protein is turned on and off at different times

what is a chromosomal mutation?

involve changes in the number of structure of chromosomes, locations of genes on chromosomes, or number of copies of genes

what is a point mutation?

involves changes in one or a few nucleotides

what happens to the mRNA prior to translation?

it is transcribed from DNA in the nucleus and released into the cytoplasm

how does ribosome reading work?

it reads the entire mRNA molceule, like an assembly line or ticker tape

what is the protein that can bind to the O region and prevent transcription?

lac repressor

what can the lac repressor also bind to?

lactose

what is a deletion?

loss of all or part of a chromosome

what does the cell use information from during translation?

mRNA to produce proteins

what are the 2 types of substitutions?

missense mutation and nonsense mutation

are operons generally found in eukaryotes?

no

what is the lac operon turned off and on by?

off by repressors, on by the presence of lactose

What is a missense mutation?

one amino acids changes in the protein

what is substitutions?

one base changed to another

in ecoli what must be expressed?

operon for the bacterium to be able to use the sugar lactose (therefore called the lac operon)

what is a translocation?

part of one chromosome breaks off and attaches to another

what have molecular biologist identified?

patterns in the DNA sequences of genes

what is a regulatory site?

place where other proteins bind directly to the DNA sequence and regulate transcription, help to determine whether a gene is turned off or on

what is transcription?

process in which a sequence of DNA is copied into a complementary sequence of RNA

what do gene mutations do?

produce changes in a single gene

what is a duplication?

produces extra copies of parts of a chromosome

what does the lac operon code for?

proteins that allow lactose to be brought across the cell membrane and broken down into its two components, glucose and galactose

what do genes code for?

proteins, which are able to build/operate components of cells

what is a inversion?

reverses the direction of parts of a chromosome

where does translation take place?

ribosomes

what is a frameshift mutation?

shift the reading frame of the DNA strand; caused by insertions and deletions; can change every amino acid and drastically alter the protein (sometimes to the point that it isn't functional)

what is the TATA box?

short region of DNA about 30 base pairs long; seems to help position RNA polymerase on the promoter and stabilize its binding

what does RNA control?

the assembly of amino acids into proteins, each type of RNA accomplishes a different job in this process

what will a point mutation cause?

the cell to make an incomplete polypeptide if the mutation results in a stop codon

what happens if lactose is present?

the lactose molecules bind to protein, which causes it to change shape and fall of the operator, enabling transcription to take place

what happens as each codon is read?

the matching amino acid is brought by a tRNA and added to the growing polypeptide

where does RNA polymerase bind?

the regions of DNA called promoters, like a start signal, similar signals in DNA to cause it to stop

what happens after the polypeptide chain stops growing?

the ribosome releases it and the mRNA molecule

what is transfer RNA?

transfers the amino acids as coded by the (mRNA) to the ribosome

how many bonding sites does the ribosome have?

two, so the next codon is also read

how long does the polypeptide grow?

until the ribosome reaches the stop codon on the mRNA strand

when does translation stop?

when a stop codon is reached

how does translation begin?

when the mRNA attatches to a ribosome, it begins at AUG the start codon