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59 terms

Chapter 9

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Alkaptonuria
autosomal recessive trait where individuals lack the enzyme to break down homogentisic acid; characterized by black urine
Neurospora
bread mold used by Beadle and Tatum to show that mutation in a specific gene caused loss of activity in a specific enzyme
Diversity of Proteins
results from the number of possible combinations of the 20 different amino acids
Protein
intermediary between genes and phenotype
Codon
triplet of nucleotides in mRNA that encode the information for a specific amino acid
T4 Genes
used by Crick & Brenner to discover the number of nucleotides required to encode one amino acid
Stop Codon
signals the end of protein synthesis
mRNA
single-stranded copy of the nucleotide sequence in a gene
Transcription
transfer of information from the base sequence of DNA to the base sequence of RNA; occurs in nucleus
Translation
conversion of information encoded in the nucleotide sequence of an mRNA molecule into the linear sequence of amino acids in a protein; occurs in cytoplasm
Transcription Initiation
an enzyme called RNA polymerase binds to a specific nucleotide sequence in the DNA adjacent to a gene and unwinds the DNA
Promoter Region
region of a DNA molecule to which RNA polymerase binds and initiates transcription
Polymerase I
catalyzes transcription for rRNA formation
Transcription Elongation
RNA polymerase links RNA nucleotides together, forming mRNA
Terminator Region
nucleotide region that signals the end of transcription
Introns
DNA sequences that are transcribed but removed during processing; noncoding
Exons
DNA sequences that are transcribed and translated into an amino acid sequence
Pre-mRNAs
precursor molecule that are processed in the nucleus to remove introns, or cut and spliced to remove introns
Cap
modified base attached to the 5' end of mRNA
Poly-A Tail
series of A nucleotides added to the 3' end of mRNA
Amino Group
chemical group (NH2) found in amino acids and at one end of the polypeptide chain
Carboxyl Group
chemical group (COOH) found in amino acids and at one end of the polypeptide chain
Peptide Bonds
covalent chemical link between carboxyl and amino groups of two different amino acids
Polypeptide
molecule made of ten or more amino acids joined together with peptide bonds
N-Terminus
end of a polypeptide or protein that has a free amino group
C-terminus
end of a polypeptide or protein that has a free carboxyl group
Ribosome
cytoplasmic particles composed of two units that are the site of protein synthesis
rRNA
RNA molecule that forms part of the ribosome
tRNA
contains a binding site for a specific type of amino acid and has a three-base segment that recognizes a specific base sequence in mRNA
Anticodon
group of three nucleotides in a tRNA molecule that pairs with a complementary sequence in an mRNA molecule
Initiation Complex
formed by a combination of mRNA, tRNA, and the small ribosomal subunit
Proteome
set of proteins present in a particular cell at as specific time under a particular set of environmental conditions
Primary Structure
amino acid sequence in a polypeptide chain; still linear
Tertiary Structure
3D structure of a protein molecule brought about by folding on itself
Secondary Structure
pleated structure in a protein molecule brought about by bonds between amino acids
Quaternary Structure
structure formed by the interaction of two or more polypeptide chains in a protein
Protein Functions
muscle contraction, transport, immune response, nerve impulse transmission, phenotypes of cells/tissues/organisms
Prion
protein folded into an infectious conformation that is the cause of several disorders
Mad Cow Disease
prion disease of cattle
Substrates
molecules that can fit into the three-dimensional shape of an enzyme
Phenylalanine Hydroxolase
the enzyme that catalyzes the conversion of phenylalanine to tyrosine
Lactase
the enzyme that catalyzes the breakdown on sugar lactose
Enzyme
lowers the energy of activation required in biochemical reactions
Genetic Disorders
absence or changes to the protein functions; mutant phenotypes
Amount of Info Stored in a Cell
related to the number of nucleotides within a cell
Protein Diversity
stems from possible combinations of the 20 amino acids
Colinear
points on the polypeptide chain mirror points on the gene; if there is a break toward the end of the gene, the chain will have a break t the same point
Degenerate
the last position can vary, but the codon will still create the same amino acid
Polymerase II
catalyzes transcription for mRNA formation
Polymerase III
catalyzes transcription for tRNA formation
Promoters
sequences that allow polymerases to bind to the DNA strand before reaching the open reading frame
Open Reading Frame
a stretch of consecutive codons undisrupted by a termination codon
Heterogeneous Nuclear RNA
newly synthesized RNA
Alternative Splicing
allows for the possibility that a single gene can produce more than one type of protein
Direction to Read a Polypeptide
from N-terminus to C-terminus
Chaperones
assist in the folding of newly synthesized proteins
Post-Translational Modification
process in which polypeptides are chemically modified after being created
Beta Sheet
the backbone of this particular secondary structure looks like an accordion
Creutzfeldt-Jakob Disease
human version of mad cow disease; brain looks like a sponge