Bio 1A Midterm 2

DNA adduct

attachment of a chemical mutagen to a nitrogenous base

dna replication

process of producing 2 identical copies from one original DNA molecule

5’ → 3’

direction new DNA strand is synthesized in

mutation

change in the DNA sequence

genome

cell’s DNA

1. mitosis is a type of cell division that promotes growth and tissue repair/ renewal

2. in adults, most specialized cells have lost the ability to divide - only stem cells can divide

3. the goal of mitosis is to create 2 cells with identical genetic information

   1. mitosis is like a copy machine

4 key ideas of mitosis

renew the outer layer of skin

example of stem cell function

chromatin

mixture of DNA and proteins that form chromosomes

chromosomes

threadlike structure made of proteins and a single molecule of DNA

homologous chromosomes

chromosomes that have all the same genes but may have different alleles of those genes

chromatid

one of the 2 identical halves of a chromosome

cell cycle

life of a cell from the time its first formed during division of a parent cell until its own division into 2 offspring cells

metabolic activity and growth

G1 phase

duplication of chromosomes (DNA synthesis)

S phase

metabolic activity, growth and preparation for cell division

G2 phase

mitosis and cytokinesis

mitotic phase

mitosis

distribution of chromosomes into identical nuclei

cytokinesis

division of the cytoplasm

centrosome

organize microtubules of the spindle

cell cycle control system

cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle

cyclins

proteins named for their cyclically fluctuating concentrations in the cell

cyclin dependent kinase

activity rises and falls with changes in concentration of its cyclin partner

maturation promoting factor (MPF)

cyclin-CDK complex that triggers a cell’s past the G2 checkpoint

cancer

disease in which some of the body’s cells grow uncontrollably

tumor supressor genes

normal genes that function to detect errors in DNA replication and respond to either correct them or undergo programmed cell death

proto-oncogenes

normal genes that function to detect and respond to signals that stimulate a cell to divide

heredity

transmission of traits from one generation to the next

variation

the difference in appearance that offspring show from parents and siblings

genetics

scientific study of heredity and variation

genes

hereditary units made of DNA that parents transmit to their offspring

locus

gene’s specific location along a chromosome

gametes

reproductive cells (sperm and eggs)

somatic cells

all cells of the body except gametes

asexual reproduction

single individual passes all of its genes to its offspring via mitosis without the fusion of gametes

clone

group of genetically identical individuals from the same parent

sexual reproduction

2 parents give rise to offspring that have unique combinations of genes inherited from 2 parents

life cycle

generation to generation sequence of stages in the reproductive history of an organism

diploid

containing 2 complete sets of chromosomes, one from each parent

law of segregation

the maternal and paternal copies of a given chromosome or gene separate during meiosis and end up in different gametes at random (with equal probability)

independent assortment

maternal and paternal chromosomes of any homologous pair segregate into gametes independently of all other homologous pairs of chromosomes

crossing over

maternal and paternal chromosomes exchange genetic information during prophase 1

1. law of segregation

2. law of independent assortment

3. crossing over

4. meiosis is like a slot machine that produces 4 genetically distinct cells

4 key ideas of meiosis

chiasmata

spots where crossing over has just occurred

cohesins

proteins that hold together sister chromatids after duplication

chance of ending up with 1 chromosome x chance of ending up with another chromosome

how do you calculate probaility

meiosis

special type of cell division that reduces the number of chromosome sets from diploid to haploid

metaphase

which phase of meiosis is independent assortment relevant to

independent assortment, crossing over and random fertilization

what 3 mechanisms contribute to genetic variation in sexual life cycles

trait

variant of a character

allele

alternative versions of heritable factors (genes)

multiplication rule

probability that two or more independent events will occur together (this and that)

addition rule

probability that any one of 2 or more mutually exclusive events will occur together

phenotype

appearance of a trait

genotype

genetic makeup of an individual

quantitative characters

characters that vary in a population along a continuum

incomplete dominance

phenotype of F1 hybrids is somewhere between the phenotypes of 2 parents

codominance

2 dominant alleles affect the phenotype in separate distinguishable ways

epistatis

expression of a gene at one locus alters the phenotypic expression of a gene at a second locus

polygenic inheritance

multiple genes affect the phenotype

pleiotrophy

a single gene has effects on multiple phenotypes

chromosome theory of inheritance

mendelian genes have specific loci along chromosomes - chromosomes undergo segregation and independent assortment

sex linked gene

gene located on either sex chromosome

hemizygous

male only needs one copy of an allele for a recessive X linked trait to be expressed

Barr body

inactive X chromosome condenses into during embryonic development

uniparental inheritance

organelle genes are inherited from one parent - ex. human mitochodria are maternally inherited via cytoplasm of the egg

linked genes

genes that are near each other on the same chromosome that deviate from Mendel’s law of independent assortment

aneuploidy

when there is an abnormal number of a particular chromosome

monosomy

(2n-1) chromosomes

trisomy

(2n+1) chromosomes

polyploidy

have multiple complete sets of chromosomes

linkage map

genetic map based on recombination frequencies

nondisjunction

pairs of homologous chromosomes do not separate normally during meiosis

polyploidy (trait)

what is important for plant diversification and speciation

deletion

removal of a chromosome segment

duplication

segment of a chromosome repeated

inversion

reverses a segment within a chromosome

translocation

moves a segment from one chromosome to a non homologous chromosome

helicase

unwinds parental double helix at replication forks

single strand binding protein

binds to and stabilizes single stranded DNA until it used as a template

topoisomerase

relieves overwinding strain ahead of replication forks by breaking, swiveling and rejoining DNA strands

primase

synthesizes an RNA primer at 5’ end of leading strand and at 5’ strand end of each Okasaki fragment of lagging strand

DNA ligase

joins Okazaki fragments of lagging strand, on leading strand, joins 3’ end of DNA that replaces primer to rest of leading strand DNA

RNA directed RNA polymerase (trait)

which enzyme can initiate transcription without a primer

regulation of enzyme activity and regulation of enzyme production

what are 2 ways that cells can control metabolic activity?

RNA polymerase 2

complex of more than 10 proteins in eukaryotic organisms that transcribes genes encoding mRNAs and some non coding mRNA (encodes most protein coding genes) and CANNOT initiate transcription by itself

core promoter

area on genes in eukaryotes where general transcription factors bind to bring RNA polymerase

general transcription factors

bind to promoter on all genes - forms transcription initiation complex

control elements (enhancers)

regions of DNA that can be close or far from core promoter that can bind specific transcription factors

transcription factors

proteins that bind to control elements that function as activators or repressors

DNA binding domain

part of transcription factor protein that interacts with DNA helix (binds to DNA)

activation domain

part of transcription factor protein that interacts with other proteins

protein mediated bending of DNA brings activators (TF) into contact with mediator proteins that interact with general transcription factors at the promoter - this protein- protein interaction positions the transcription initiation complex on the promoter

how do general TFs and TF interact to initiate transcription?

each cell type contains a different group of activators that determine which gene is expressed

how do eukaryotic genes control which genes are expressed during transcription

every gene in the group has shared control elements/ enhancers ex. - Gal4 binds upstream to all genes

how is gene expression coordinated between different genes in eukaryotes?

alternative RNA splicing

different mRNA molecules are produced from the same primary transcript depending on which segments are treated as exons and introns

rate of synthesis (transcription and processing) and rate of degration

what does steady state level of mRNA depend on

steady state level

amount of RNA present at any given point in time

miRNA

short noncoding mRNA that regulate RNA degradation and translation

RISC

miRNA is assembled into this and either cleaves mRNA that is degraded by exonucleases or blocks ribosomes from translating mRNA

genes are organized in operons and have TATA box and tata binding protein, have histones and simplified chromatin, specific transcription factors resemble bacteria TF in structure and action,

what are features of gene expression in archea