Chapter 21 Flashcards
*DNA (in nucleus) to mRNA (moves from nucleus to cytoplasm) to protein (in cytoplasm)
*DNA -> RNA -> Protein
flow of information
central dogma
Made of Nucleic acids
DNA
Nucleotides make what?
Nucleic Acids
Deoxyribonucleic acid
DNA
Ribonucleic Acid
RNA
Adenine, Guanine, Cytosine, Thymine
DNA
Adenine, Guanine, Cytosine, Uracil
RNA
Purine (A&G) and Pyrimidine (T&C)
Two Forms of Nucleotides in DNA
2 hydrogen bonds
A-T
3 hydrogen bonds
G-C
is arranged in a double helix
DNA nucleotides
Double Helix discovered by
Watson and Crick
dictates sequences on one strand
complementary base pairing
these can line up in any order on a strand
nucleotides
5’- G C A C C A A T A - 3’
3’- C G T G G T T A T - 5’
complementary base pairing
nucleotide sequence in a DNA molecule that codes for a specific polypeptide chain
Gene
Genes consist of two strands, what are they?
coding and template
carry information for making proteins in our body
DNA
information for making proteins is organized into localized regions along DNA molecule called what?
genes
Each ______ has information for making a protein or RNA
gene
Each ____ molecule has many genes
DNA
There are about how many genes in the human body?
~ 23,000
These areas may have some other function; some areas of DNA do not have instructions for making RNA or Protein and are not
genes
DNA molecules are called what when dividing?
chromosomes
have 23 pairs of chromosomes and 46 chromosomes in total
Human Cells
process of copying DNA prior to cell division
DNA replication
this and other proteins unwind DNA Molecule
Helicase
catalyzing the reaction that puts monomers together, making polymers
polymerase
use one molecule of DNA as a template
semiconservative replication
DNA repair is carried out by _____________ and other _______
DNA Polymerase and enzymes
small-scale change in the nucleotide sequence of a gene
Gene Mutation
Specific nucleotides for _______, which are hydrogen molecules bonded together
base pairs
DNA to RNA
transcription
These processes convert DNA information into proteins
transcription and translation
gene serves as a template for RNA synthesis, occurs in the nucleus using RNA polymerase
transcription
joins nucleotides together until termination sequence is reached; begins at promoter region
RNA Polymerase
sequences for the proteins
exons
Pre-mRNA contains what?
Introns and Exons
Each cell determines which genes are …?
active or inactive
*speed up or halt transcription
*may bind with noncoding DNA sequences and affect the transcription of a neighboring gene
regulatory proteins
helps to fight inflammation; works with the immune system
Glucocorticoid
When a gene is not active –> no ______ is being made
RNA
carries DNA gene information out of the nucleus to the ribosomes in the cytoplasm or rER
mRNA
Three bases on mRNA, they are decoded three at a time
codon
AUG
start codon
what does a start codon do?
establishes the reading frame for translation
Codons that do not connect with other codons
stop codons
delivers the “right” amino acid to the correct location along the mRNA/ribosome complex (decodes mRNA)
tRNA
component of catalytically active ribosome enzyme
rRNA
these are adapters between amino acids and the codons in mRNA molecules
tRNAs
anticodon of _____ base pairs w/ codon of ________.
tRNA; mRNA
amino acid is covalently attached to this end of the tRNA
3’
*two subunits are built in the nucleus from rRNA and proteins
*shipped to the cytoplasm
*combine into _______ during translation
ribosomes
What is a ribosome made of?
RNA and Proteins
have a free amino group, free carboxyl group, and a side group
Amino acids
polypeptide is a long chain of?
amino acids
amino acids are joined by
peptide bonds
this group of one amino acid is covalently attached to the amino group of the next amino acid
carboxyl group
*AUG binds w/ the small ribosome unit
*large ribosome subunit binds to the initiation complex
*initiator tRNA w/AUG attached binds to mRNA codon
Initiation
Peptide bonds form between incoming amino acids
Elongation
detachment of the new polypeptide; stop codon
Termination
Where do new polypeptide chains go?
some stay in the cytoplasm
others modified in the ER to be sent out of the cell
cluster of ribosomes all translating the same mRNA at the same time
Polysomes
This binds to the AUG initiation codon
methionine
Translation usually begins here
first AUG
small ribosomal subunit from here
5’ terminus of mRNA
aminoacyl-tRNA entry site
incoming tRNA binding site
A site
peptidyl-tRNA site
holds the growing peptide chain
P site
exit site of tRNA
E site
polypeptide chain termination occurs when?
a chain-termination (stop) codon enters the A site of ribosome
what molecule is added to the carboxyl terminus of the nascent peptide causing termination?
water molecule
DNA polymerases and other enzymes repair replication mistakes
DNA repair
a change in the sequence of a Gene’s nucleotides
mutation
an incorrect nucleotide is paired with an exposed base during DNA replication; may be repaired; if not one amino acid may replace another during translation
Base Pair Substitution
a base is lost; could alter the reading frame
Deletion
Single-base pair insertion; alters the reading frame
insertion