ap bio unit 6

operons

a group of genes that can be turned on or off

three parts: promoter, operator, genes

promoter

area where RNA polymerase can attach to operons

operator

the on/off switch on operons

genes

code for related enzymes in pathway on operons

regulatory gene

produces a repressor protein that binds to the operator to block RNA polymerase form transcribing the genes

can be reversible

allosteric activator

substrate binds to allosteric site and stabilizers the shape of the enzyme so that the active sites remain open

allows enzyme to accept substrate

allosteric site

location on an enzyme that is NOT the active site

allosteric inhibitor

substrate binds to allosteric site and stabilizers the enzyme shape so that the active sites are closed (inactive form)

changes shape of enzyme and prevents substrate from binding

active site

the location on an enzyme where substrate binds

histone acetylation

the addition acetyl groups to histones, loosening the DNA

histones

proteins that DNA wraps around

DNA methylation

the addition of methyl groups to DNA, causing chromatin to condense

epigenetic inheritance

the passing of chromatin modifications, not nucleotide sequence, from parents to offspring

ex.) histone acetylation, DNA methylation

control elements

sections of noncoding DNA that serve as binding sites to begin transcription

initiation factors

translation is activated or repressed by these

ex.) microRNAs and small interfering RNAs can block translation

cell differentiation

when cells become specialized in their structure and function

morphogenesis

the physical process that gives an organism its shape

cytoplasmic determinants

substances in the maternal egg that influence cells

induction

cell to cell signals that cause a change in gene expression

pattern formation

a body plan for the organism

homeotic genes

genes that map out body structures

apoptosis

programmed cell death

allows structures to take form initially, but will remove extra features later on

mutations

changes in the genetic material of a cell, which can alter phenotypes

primary source of genetic variation

point / small scale mutations

types of small scale mutations where only one single nucleotide pair of a gene is changed

substitution —> silent, missense, nonsense

substitution

type of point mutation where the replacement of one nucleotide and its partner with another pair of nucleotides

silent mutation

type of substitution mutation where the change still codes for the same amino acid

no noticeable change in phenotype

amino acid redundancy

since there are 20 amino acids, many different combinations of codons will code for the same amino acid

causes silent mutations

missense

a type of substitution mutation where the change results in one different amino acid in the sequence

nonsense

a type of substitution mutation where the change results in an early stop codon

frameshift mutation

a type of point mutation where the reading frame of genetic information is altered

disastrous effects to proteins

insertion and deletion

insertion

type of frameshift mutation where a nucleotide is added to the sequence, changing the reading frame

deletion

a type of frameshift mutation where a nucleotide is removed from the sequence, changing the reading frame

large scale mutations

mutations that affect entire chromosomes

nondisjunction

a type of large scale mutations when chromosomes do not separately properly in meiosis, resulting in the incorrect number of chromosomes

translocation

a type of large scale mutations where a segment of one chromosome moves to another

inversions

a type of large scale mutations where a segment of the chromosome is reversed

duplications

a type of large scale mutations where a segment of the chromosome is repeated

deletions

a type of large scale mutations where a segment of the chromosome is lost

horizontal gene transfer

the way in which prokaryotes can exchange genetic material with each other

transformation

a type of horizontal gene transfer where one prokaryote uptakes the DNA from a nearby dead cell

transduction

type of horizontal gene transfer where genetic is transferred to a prokaryote via a virus

conjugation

type of horizontal gene transfer where two living prokaryotes exchange DNA

transposition

type of horizontal gene transfer where DNA segments are transferred between DNA molecules

gel electrophoresis

a technique used to separate and analyze DNA fragments by size

polymerase chain reaction (PCR)

a method used in molecular biology to make several copies of a specific DNA segment

DNA sequencing

the process of determining the order of nucleotides in a DNA sequence