Chapter 8 Microbio

nucleotides

building blocks of DNA and RNA made of a sugar

nitrogenous base

part of a nucleotide that carries genetic information (A

adenine

one of the four DNA bases that pairs with thymine

guanine

one of the four DNA bases that pairs with cytosine

cytosine

one of the four DNA bases that pairs with guanine

thymine

one of the four DNA bases that pairs with adenine

antiparallel

describes DNA strands running in opposite directions

complementary

means the bases pair specifically (A with T

semiconservative replication

when DNA copies itself

oriC

the starting point of DNA replication in bacteria

DnaA

protein that starts DNA replication by opening the DNA at oriC

DnaB (helicase)

enzyme that unwinds the DNA double helix

DnaG (primase)

enzyme that makes short RNA primers for DNA synthesis

single-stranded DNA-binding proteins

keep DNA strands apart during replication

replication bubble

opened area of DNA where replication happens

DNA polymerase

enzyme that builds new DNA strands

primer

short RNA piece that helps DNA polymerase start copying

leading strand

DNA strand made continuously in replication

lagging strand

DNA strand made in small pieces (Okazaki fragments)

Okazaki fragments

short DNA segments made on the lagging strand

ligase

enzyme that connects Okazaki fragments together

telomere

protective end of a chromosome that prevents damage

telomerase

enzyme that rebuilds telomeres after DNA replication

transcription

process where DNA is copied into RNA

gene

a DNA section that codes for a specific protein or trait

uracil

RNA base that replaces thymine

messenger RNA (mRNA)

carries genetic info from DNA to the ribosome

transfer RNA (tRNA)

brings amino acids to the ribosome during translation

ribosomal RNA (rRNA)

main part of the ribosome that helps make proteins

microRNAs (miRNA)

small RNA molecules that control gene expression

RNA polymerase

enzyme that makes RNA from a DNA template

promoters

DNA regions that tell RNA polymerase where to start transcription

sigma factor

protein that helps RNA polymerase bind to the promoter in bacteria

transcription factors

proteins that control when and how genes are turned on

5’ cap

special structure added to the start of mRNA for protection and recognition

3’ poly(A) tail

string of A’s added to the end of mRNA for stability

introns

noncoding parts of RNA removed before translation

exons

coding parts of RNA that stay and are used to make protein

post-transcriptional modifications

RNA changes after transcription (like adding caps

translation

process where mRNA is used to build proteins

ribosomes

cellular structures that assemble proteins

codons

three-letter mRNA sequences that code for amino acids

anticodon

three-letter tRNA sequence that pairs with a codon

amino acid

building block of proteins

Shine-Dalgarno sequence

bacterial mRNA region where ribosome binds to start translation

stop codon

signal that ends protein synthesis

polycistronic

mRNA that codes for multiple proteins (common in bacteria)

monocistronic

mRNA that codes for one protein (common in eukaryotes)

heat shock proteins

help protect and refold damaged proteins under stress

phosphorylation

adding a phosphate group to a protein to change its activity

base substitution

one DNA base is swapped for another

missense mutation

base change that results in a different amino acid

silent mutation

base change that doesn’t affect the amino acid

nonsense mutation

base change that creates a stop codon

insertions

adding extra DNA bases

deletions

removing DNA bases

frameshift mutations

insertion or deletion that shifts how codons are read

inversions

DNA segment is flipped in the chromosome

translocations

DNA piece moves to a different chromosome

proofreading

DNA polymerase checking and fixing mistakes as it copies

mismatch repair

system that fixes base-pairing mistakes after replication

mutagens

things like radiation or chemicals that cause DNA mutations