biology 1 Flashcards
Where is DNA held?
nucleus
A small amount of nuclear DNA is found in the __
mitochondria
What is the nucleolus?
the site of rRNA transcription and ribosome assembly
Where are proteins that are bound to the ER, golgi, lysosomes, endosomes, plasma membrane or secreted outside the cell made?
the RER
Where are proteins that remain in the cytosol made?
free floating ribosomes
Where in the cell are lipids synthesized?
smooth ER
Where are lipids metabolized?
in the mitochondria
What is the function of the golgi apparatus?
organize and distribute proteins, continue post translational modification
How are mitochondrial genes passed down?
maternal side
What is the endosymbiotic theory?
suggests mitochondria evolved from aerobic prokaryotes that were engulfed by a larger host.
Where is the pH higher, the matrix or the inter membrane space of the mitochondria?
matrix has higher pH (protons are pumped into intermembrane space)
What would happen if hydrogen ion channels were placed in the mito mem?
less ATP production because there would be an alternate route from ATP synthase
What is thermogenin?
protein channel in the inner membrane of mito that allows the passage of protons (brown fat)
What are the main functions of centrioles/centrosomes?
centrosome - organizes microtubules, flagella, and cilia (plays key role in cell division)
What is the pH of a lysosome? What is its function?
5, digest cell parts, fuse with phagocytic vesicles, participate in apoptosis
What is the function of peroxisomes?
self-replicate, detoxify chemicals, participate in lipid metabolism
What is tubulin?
a globular protein that polymerizes to form microtubules
What are microtubules?
make up the cytoskeleton, 2 types of tubulin: alpha -tubulin, beta-tubulin
protofilmament- heterodimer
How many protofilaments in a microtubule?
13
What is the cytoskeleton?
scaffolding-like network of microfilaments, microtubules, and intermediate filaments that provides structure to the cell
What is the spindle apparatus?
array of microtubules that grows outwards from the centrioles during mitosis to bind with the centromere of the chromosomes at the metaphase plate
What is actin?
protein monomer that polymerizes to form microfilaments
What is an intermediate filament?
general class of several proteins that polymerize to form filaments that are intermediate in diameter.
What is myosin?
motor protein (9+2) arrangement found in eukaryotic cilia and flagella
What is the difference between flagella and cilia?
flagella - used for locomotion (sperm)
cilia - beating pattern - moves fluids and other substances past the cell
In humans, where is cilia found?
- respiratory system (lungs)
- nervous system (ependymal cells)
- reproductive system (uterine tubes)
What problems would a disease that prevented microtubule production cause?
weakened cytoskeletons, would not be able to complete mitosis or meiosis, ciliated epithelial cells would lose their function
What is the difference between the movement of eukaryotic and prokaryotic flagella?
eukaryotic- whipping motion - microtubules made of tubulin
prokaryotic - spinning/rotating motion- simple helices made of flagellin
describe the fluid mosaic of the phospholipid bilayer
phospholipids are mobile and can exchange positions with each other and move laterally across the leaflets
What is the difference between simple and facilitated diffusion?
simple- NO ATP required (relies on concentration gradient)
facilitated - NO ATP required (needs proteins in the membrane)
What is the difference between a hypertonic, hypotonic, and isotonic solution?
hyper- more solute
hypo- less solute
iso- no net flow of water in either direction
What characterizes active transport?
required when something is moved against its concentration gradient or against an electrical potential
What is secondary active tranport?
no direct coupling of ATP required
what are tight junctions, gap junctions, and adherens junctions?
tight - water-proof barriers
gap- tunnels between adjacent cells allowing exchange
adherens - strong mechanical attachments
What is the strongest type of cellular junctions?
desmosomes
Where are tight junctions found in the body?
epidermis of the skin
Where are gap junctions found in the body?
junctions between cardiac muscle or smooth muscle
Where are adherens junctions found in the body?
epithelium and between cardiac muscle cells
Where are desmosomes found in the body?
epidermis (stratified epithelium)
What type of tissue is blood? adipose tissue?
both connective tissue
describe the G-protein cascade
- signal molecule binds to an IMP (GPCR)
- causes conformational change that activates the cytosolic domain
- G protein (alpha subunit binds both GTP and GDP), signal causes GTP to substitute GDP, activating the alpha subunit and separates from beta and gamma subunits
- g protein is agonist for adenylyl cyclase - makes cAMP from ATP
- cAMP is agonist for PKA, which phosphorylates proteins
What is a paracrine signal?
signal molecules secreted by one cell bind to receptors on other cells in a local area (NT in synapse)
What is autocrine signaling?
signal secreted by cell bind to receptors on the same cell
What is intracrine signaling ?
signal molecules (usually steroids) bind to receptors inside the same cell that produced them, without being secreted outside.
What is juxtacrine signaling?
signaling requires direct contact between two cells
Describe the cell cycle. What is G0 phase?
G1 (growth)- S (synthesis)- G2 (growth, high metabolic activity) - M (mitosis)
G0- not actively dividing (differentiated cells)
What is a histone?
proteins around which the DNA helix is wrapped during the first step of DNA condensation
What is a nucleosome?
set of 8 histone proteins in a cube shape with DNA coiled around it
What are homologues and sister chromatids?
homologues - two related but non-identical chromosomes
sister chromatids - identical
What is the difference between the kinetochore and the centromere?
centromere- region of the chromosome that joins the sister chromatids
kinetochore - group of proteins where spindle fibers attach to during mitosis and meiosis
When does crossing over occur?
prophase 1
What is nondisjunction and when can it occur?
chromosomes fail to separate properly during anaphase during meiosis 1, meiosis 2, or mitosis
What are the 3 components of the nucleotide?
phosphate backbone, sugar and nitrogenous base
What other biomolecules, besides RNA and DNA, are nucleotides?
cAMP, NADH, FADH2, FMN, coenzyme A, ATP, GTP, UTP
How many hydrogen bonds between AT?
How many hydrogen bonds between GC?
2 AT
3 GC
What does semi-conservative replication mean?
each newly formed daughter helices consists of one original strand paired with one newly-replicated strand
What does semi-discontinuous replication mean?
one strand is synthesized continuously and the other strand is synthesized in Okazaki fragments
What does the enzyme RNase H do in DNA replication?
removes RNA primers
In DNA replication, what direction is DNA read and what direction is it replicated?
read- 3’- 5’
made - 5’ -3’
Why does the newly replicated strand of DNA become shorter than the parent strand?
5’ end of DNA does not have existing free 3’ hydroxyl so DNA polymerase cannot replace that section of primer
What is the enzyme that adds length to telomeres?
telomerase
What are the 3 causes of DNA damage?
spontaneous hydrolysis, damage by external chemicals or radiation, mismatched base pairs
What causes mismatched base pairs in DNA?
errors during replication or methylation of guanine
How do chemicals or radiation impact DNA?
radiation - neighboring pyrimidines react to form covalent dimers
carcinogens- bind to DNA (bulky side groups)
What are the 4 mechanisms of DNA repair?
proofreading - DNA polymerase catches and repairs most mismatched pairs
mismatch repair system- enzymes that scan newly copied DNA, and locate, excise and replace mismatched pairs
base excision- base only excised first via DNA glycosylase , other enzymes remove sugar-phosphate backbone, then DNA polymerase and ligase replace nucleotide
Nucleotide excision - excision of an oligonucleotide that includes several bases on either side of the error
Explain the steps of PCR
- DNA heated to 95 celcius to unwind
- primers are added (2- one for 3’ of sense one for 3’ antisense) cooled down to (50-65 celcius)
- temp raised to 72 celcius for taq polymerase to polymerize DNA
- repeat cycle
What piece of information must be known in order to perform PCR?
the exact DNA squence
What is a southern blot used for?
used to verify the presence/absence of specific DNA sequence and indicate size of restriction fragments
what is the northern blot used for?
nearly identical of southern blot, used on RNA instead of DNA
What is the western blot used for?
used on protein segments instead of nucleotides. the probes are radiolabeled antibodies rather than nucleotide sequences
What is an eastern blot used for?
similar to western blot, but used to verify post-translational modification. the probes used bind to lipids, carbs and phosphates
What are the differences between DNA and RNA?
RNA- 2’ OH group, single stranded, uracil, exits nucleus into the cytoplasm
DNA - always stays in the nucleus, thymine, double stranded
What is the function of rRNA?
rRNA- polymer of which ribosomes are made, ribosomes are assembled in the nucleolus
What is the function of tRNA?
has anti-codon and covalently bonded amino acid on one end. Assists in translation of proteins
What is the function of mRNA?
complementary RNA strand copied from DNA template strand.
What is alternate splicing?
after introns are removed from mRNA transcript, the exons can be assembled in a number of different orders, each results to a different protein
What are other terms for template strand?
anti-coding, anti-sense
The Lac operon codes for__
translation of lactase
Will the lactase gene be transcribed in the presence of glucose but no lactose?
no, inhibitor is bound
Will the lactase gene transcribed in the presence of lactose and no glucose?
yes
Will the lactase gene transcribed in the presence of no glucose or lactose?
no
Will the lactase gene transcribed in the presence of lactose and glucose?
no, inhibitor would not be bound, but cAMP levels (activator) will be low when glucose is present
What 3 mechanisms are genes regulated by?
rate of transcription- RNA has short half life, gene only expressed if DNA is continuously transcribed
activators or repressors- regulatory molecules up regulate transcription (hormones, lactose, glucose)
permanent or semi-permanent suppression - methylation or other covalent modification
What are the 3 stop codons?
UGA, UAG, UAA
What does it mean when the human genetic code is described as degenerative and unambiguous?
degenerative- redundant (multiple codons can code for same aa)
unambiguous - the aa is known by the codon
What are the 3 sites of the ribosome in translation?
aminoacyl, peptidyl, exit site
APE
In translation, which direction does the ribosome read the mRNA?
5’ to 3’
What is the enzyme that charges the tRNA during translation?
aminoacyl-tRNA synthetase
Where does translation occur?
cytoplasm
Where does post-translation modification occur?
ER and golgi apparatus
What is a mutation?
any change in the DNA sequence
what is a point mutation?
single base pair substitution
What is a missense mutation?
changes the codon so that a different amino acid will be incorporated
What is a silent mutation?
does NOT alter amino acid sequence
What is a frameshift mutation?
changes the reading frame
What is a neutral mutation?
does not negatively impact the fitness of the individual
What is a nonsense mutation?
changes normal codon to a premature stop codon
What is a proto-oncogene?
normal genes that regulate cell division, cell cycle, growth, apoptosis
What are tumor suppressor genes?
help protect the cell from uncontrolled growth, they require 2 recessive alleles to lose function
What is the mendelian ratio ?
3: 1 phenotypic ratio
1: 2:1 genotypic ratio
What is a test cross?
cross between a homozygous recessive and an individual with at least one dominant allele
What is the law of segregation?
Alleles segregate independently of one another when forming gametes
What is the law of independent assortment?
Genes located on different chromosomes assort independently
If a genetic problem has BOTH or AND
multiply probabilities together
If a genetic problem has EITHER (OR) how do you solve?
add probabilities together
What is incomplete dominance?
phenotypes of the dominant and recessive alleles appear to be mixed or blended in the phenotype of a heterozygote. (roses)
What is genetic co-dominance?
both phenotypes are expressed fully at the same in a heterozygote (blood antigens)
What is incomplete penetrance in genetics?
occurs when various individuals all have identical genotypes and yet some have the disease phenotype and others don’t
What is limited expressivity in genetics?
various individuals all have the same genotype AND all have the disease phenotype but they are impacted by varying degrees
What does polygenic mean?
many genes contribute to one trait
What is pleiotropy?
one single gene contributes to multiple traits
What is mosaicism?
different cells within the same individual contain non-identical genotypes
What does epigenetic mean?
heritable phenotype resulting from any process other than a change in DNA itself
What is genetic imprinting?
when one specific gene is expressed differently depending on which parent it originated from
In order for natural selection to occur:
- One individual must have a polymorphism that provides an evolutionary fitness advantage
2) That advantage must result in the individual with the favored polymorphism differentially producing more offspring.
What is a gene pool?
complete set of genes and alleles in a population
What is adaptive radiation?
rapid formation of a variety of species from one ancestral species - usually characterized by a strong environment -species connection
What is evolutionary bottleneck?
sudden decrease in the number of individuals in a population
What is genetic drift?
change in the allele frequency within a population due to random, non-genetic, non-selective factors
What is convergent evolution?
when two species arrive at a point where they have similar functional forms, but they have developed those similar forms via evolutionary pathways
What is divergent evolution?
species develop different forms AND form new species, all radiating from same common ancestor
What are the 5 Hardy Weinberg assumptions?
1) Large population
2) No mutation
3) No immigration or emigration
4) Random mating
5) No natural selection
What are the Hardy Weinberg equations?
p2 + 2pq + q2 = 1
p+ q= 1
p2- fraction of individuals who have TT
q2- fraction of individuals who have tt
2pq- Tt
What is the order of classification starting from kingdom?
Kingdom, Phylum, Class, Order, Family, Genus, Species
What is phylogeny?
a shared evolutionary history can reveal similarities
All fungi are ____
heterotrophs
fungi have cell ___ made of __
walls; chitin
how do yeasts reproduce?
budding
What is mutualism?
a form of symbiosis where both participants benefit equally
What is commensalism?
symbiosis in which one participant benefits and the other participants experience is neutral
What is parasitism?
a symbiosis where one participant benefits at the expense of the other
What is a lichen?
symbiosis between fungi and algae
What is mycorrhizae?
symbiosis between fungi and plant roots
What are the structural differences between HIV and a bacteriophage?
HIV- small spherical enveloped virus, reverse transcriptase, RNA
bacteriophage- capsid head, tail, tail fibers
Difference between lytic and lysogenic cycle
lytic - viral genes are actively transcribed and new viruses are assembled
lysogenic - dormant cycle, viral DNA is incorporated
What are the 3 ways bacteria reproduce?
conjugation- One bacteria must have an F plasmid (F+); the F plasmid is a plasmid containing the gene for a sex pilus. The recipient can be (F-)
Transformation: Bacteria pick up DNA from the environment.
Transduction: Viruses accidentally incorporate host genetic material into their nucleic acids.
Difference between gram positive and gram negative
Gram pos- - Stain purple • Very thick cell wall • Form endospores • Single cell membrane
gram neg- • Stain pink • Relatively thin cell wall • Do NOT form endospores • Contain two (2) cell membranes: one inside the cell wall and one outside the cell wall.
