Tetrads line up SINGLE-FILE at metaphase plate
Metaphase of Mitosis
Key word: “Single File”
What are the 3 main functions of PEROXISOMES?
- Detoxify chemicals
- Participate in lipid METABOLISM
- along with mitochondria
- is indicated by:
- the nuclear membranes beginning to reform and
- the chromosomes unwinding
- Formation of the NUCLEOLUS
Many diagrams will also show the beginning of cytokinesis
What are Heterotrophs?
- UNABLE to fix CO2 (like autotrophs can)
Therefore, heterotrophs must INGEST organic molecules (such as carbohydrates) as their carbon source
- Describe DNA ligase
Creates the LAST necessary PHOSPHODIESTER bond to the downstream neighbor
thus creating a COMPLETED strand! Yayyy!!!
What is the Endosymbiotic Theory?
- suggests mitochondria evolved from aerobic PROkaryotes
- …that were engulfed by an ancient EUKaryotic cell (common ancestor)
Causes of DNA Damage
- Mismatched Base pairs result from (2)?
HINT: One of the 2 causes results from a specific thing happening to a specific NT…
- Give an example of this happening (with actual BP’s, not a real-life example)
- Errors during replication, or
- Methylation of guanine
ex: one form of methylated guanine pairs with thymine INSTEAD of cytosine…whoopsy daisy
DNA replication: sliding clamp
protein that keeps DNA poly tightly bound to strand
How does reproduction work in Prokaryotes (Bacteria)?
- How does the distribution of DNA work?
Bacteria reproduce via binary fission
NO mitosis OR meiosis!
Distribution of extrachromosomal DNA (aka plasmids) is RANDOM
- Daughter cells may or may not receive a copy
What is PINOCYTOSIS?
- extracellular fluid
- very small particles
occurs in ALL cells
How does mRNA interact with DNA?
is the complementary RNA strand
…COPIED FROM the DNA template strand
a protein monomer that polymerizes to form MICROFILAMENTS
How many layers must you go through to get from outside of the cell to the nucleus?
- 2 for cell membrane
- 2 for outer nuclear membrane
- 2 for inner nuclear membrane
Fungi have cell ___ made of ___
cell walls made of chitin
What are Integral proteins?
- What is its opposite?
Proteins that have one or more segments embedded within each phospholipid bilayer
- opposite=surface/peripheral proteins
Chromosomes generally _____in size, with ______ being by far the largest
generally DECREASE in size, with chromosome One being by far the largest
The Cytoskeleton consists of?
- Intermediate Filaments (IMF’s)
If 90 out of every 1,000 individuals in a population have a RECESSIVE phenotype (tt)
- what % of pop is TT, Tt, and tt?
(Solve using HW equations)
- 90/1000=.09 √.09=.3
- therefore q=.3
- since p+q=1
- p = .72
- therefore, 49% of pop have genotype TT
- 42% are Tt
- 9% are tt
70% of alleles are p and 30% of alleles are q
In gene regulation, regulatory molecules are often what 3 things?
Regulatory molecules are often:
- Upstream products of rxn or cascade that is catalyzed by gene product
- Byproducts that build up when the  of the gene product is low
How many protofilaments surrounding a hollow core make up a microtubule?
What are Adherens junctions?
attachments b/t cells
- Meiosis I
- Interphase I
- usually occurs at?
- what are some common modifications?
- Occurs at:
- ER and the Golgi
Includes ADDITION of:
- lipids, or
Compare anaphase for meiosis I & mitosis
- SINGLE CHROMATIDS are pulled to opposite ends of cell
- TETRADS are pulled to opposite ends of cell
- Describe Endocrine
Hormones made & secreted by cells in endocrine gland, then
- Travel in bloodstream
- Bind to receptors either on:
- cell surface
- for water-soluble hormones
- inside the cell
- for lipid soluble hormones
- cell surface
What is Bidirectional (DNA replication)?
- Refers to fact that DNA replication proceeds in both directions (5→3, 3→5) simultaneously
- Starting from the origin
Name Mendel’s Laws (2)
- Law of…
- Law of Segregation
- Law of Independent Assortment
- Have a pH of what?
- What are the 3 main functions of Lysosomes?
- pH of 5
- Digest cell parts
- Fuse with phagocytotic vesicles
- participate in apoptosis
Metaphase is indicated by:
- the chromosomes lining up at the metaphase plate and
- formation of the spindle apparatus
- An individual having two different alleles of a particular gene or genes
- and so giving rise to varying offspring
Would be a…?
- Describe the G1 Phase
- Most active cells ___ and ___ within this phase
First growth phase
- most active cells LIVE and FUNCTION*
- while in this phase*
- Cell grows a ton in size during G1!
Describe what happens during CROSSING-OVER
- When does Crossing-Over occur?
TETRADS PAIR UP with one another
and exchange segments of DNA
Occurs during Prophase 1 of Meiosis
The NUCLEOLUS is the site of what 2 things?
Nucleolus= Nucleus WITHIN the Nucleus!
- rRNA TRANSCRIPTION
- Ribosome assembly
Mechanisms of DNA Repair:
- Describe Proofreading
- DNA polymerase catches and repairs most mismatched base pairs…
RIGHT AS IT HAPPENS!
Phases of Mitosis:
- What phase is it if you see:
- a single cell
- with a well-defined nuclear membrane and
- uncoiled chromosomes?
Lipids are made/ synthesized in the _____,
but metabolized in the _____
- made in SER
- metabolized in the mitochondria
What are ISOTONIC solutions?
- Which direction does water flow?
have an equal  as the cell
- so there is NO net flow of water in EITHER direction
DNA is a polymer of WHAT?
Why would fungi alternate b/t sexual & asexual reproduction?
- Basically, what are the pros & cons of each?
Sexual is hard
- but provides BETTER diversification
Asexual is easy (in terms of energy)
- but provides NO diversity
How many primers do the Leading and Lagging strands require, respectively?
The Leading strand
- only needs ONE primer
The Lagging strand
- needs MULTIPLE primers
- one for each okazaki fragment
Define the Spindle apparatus
- is array of MT’s that grow outward*
- from centrioles during mitosis*
- centrioles bind with centromeres
- induce division of a tetrad
- into separate chromosomes
Describe the 4 steps of PCR
- What does HEATING the DNA do?
- Where do you add Taq Polymerase?
- What does COOLING the mixture do?
- Heat DNA
- denatures helix
- Add primers
- using Taq polymerase
- Cool mixture
- this anneals (recombines) primers
- Heat again
Polymerase then copies DNA
- making 2 new DNA helices
- repeat many times over*
Where in the KIDNEY are the following:
- renal medulla
- renal pelvis
- renal cortex
is mostly in renal CORTEX, but dips down into the renal MEDULLA as well
- What do Single-Stranded Binding Proteins (SSBP’s) do? 2 things
- COAT the individual strands
- PREVENT them from re-annealing (unwinding)
Main components of all viruses:
- What 2 things do ALL viruses contain?
ALL VIRUSES HAVE:
- Some form of NUCLEIC ACID
- RNA or DNA
- but never BOTH
- RNA or DNA
- Plus PROTEINS
- Mechanisms of DNA Repair:
Describe (in general) how Nucleotide excision repair works
- What gets removed?
- Is that the ONLY thing that gets removed?
- What does the repairing?
- Removal of an oligonucleotide
- …that includes SEVERAL BASES on*
EITHER side of the error! (look at pic)
- DNA poly & ligase repair the missing segment
- What is a vector?
- Often, the vector is a _____
- is a segment of DNA used to transfer a desired sequence into another cell
- often, the vector is a plasmid*
Name the 4 types of Cellular Junctions?
- Tight Junctions
- Gap junctions
- Adherens junctions
Mechanisms of DNA Repair: Mismatch repair system
enzymes that scan newly copied DNA and locate, remove, and replace mismatched base pairs that DNA poly misses during proofreading
programmed cell death, courtesy of lysosomes
Mitochondria have their own ___?
- How are these passed down?
- Have their OWN DNA and variations to nuclear genetic code
- Mitochondrial genes are passed down through MATERNAL LINE ONLY
is the molecule that bridges gap b/t mature mRNA and assembled protein
Cause of DNA Damage: Damage by external chemicals or radiationgive an example
when exposed to radiation, neighboring pyrimidines (C or T) react with e/o to form a covalent dimerex: carcinogens are cpds that bind to DNA and create bulky side groups
What IS the Cytoskeleton?
(What does it DO for the cell?)
Is a scaffolding-like network of microfilaments, microtubules, and IMF’s
- gives structure to cell
- creates a “highway”
- …for intracellular transport
Cause of DNA Damage: Spontaneous hydrolysisgive an example
DNA reacts in solutions w/o external stimulus or chemicals ex: amine groups on DNA bases can react with water to form a carbonyl; via hydrolysis the entire DNA base can be replaced with an OH group
How many chromosomes do humans have…during interphase
DNA polymerase can only add to an existing ______ group
3’ OH group
form of symbiosis in which one participant benefits and the other’s experience is neutral (not good, not bad. It’s whatevs)
Human taxonomy”All Cool Men Prefer Having Heavy Sideburns”
Differences b/t DNA & RNA (4)
-RNA has a 2’ OH group, DNA does not-RNA is single stranded, DNA is double stranded-RNA has uracil bases, DNA has thymine basesRNA exits nucleus into the cytoplasm, DNA always stays in nucleus
Basic structure of bacteria
Capsule, peptidoglycan cell wall, plasma membrane, no complex-bound organelles, single circular DNA chromosome, tiny circular DNA molecules called plasmids
can capture their own energy directly from the sun via photosynthesis
specialized group of proteins to which spindle fibers attach during mitosis/meiosisoften, kinetochore is used synonymously with “centromere”
when a molecule has both polar and non polar regions (like a lipid bilayer)
two related, but non-identical chromosomes–one originating from EACH parent
How many chromosomes in a diploid cell?
Fluid mosaic model
On phospholipid membrane, there are two opposite facing leaflets with polar tails of the phospholipids directed towards center of bi-layer & polar heads sticking outward-creates both a cytosolic & extracellular face
What does “quiescent” mean? What’s an example of this?
Means stable, not changing, & unlikely to changeex: G0 phase of cell cycle
Aerobic respiration reactants (2) & products (3)
reactants: glucose & oxygenproducts: CO2, water, ATP
Anaerobic respiration reactants & products
Reacs: Glucose, electron acceptor (anything BUT oxygen)Products: CO2, whatever “thing” (which gets reduced), and ATP
Sister chromatids are?are they identical?
2 strands of DNA in a duplicated chromosome attached by a centromerethey are identical only if crossing over has NOT occured
In short, crossing over does what?
takes a father’s and mother’s chromosomes & swaps segments of them, thus creating new combinations of alleles on chromosomes
Bacteria reproduce via ?
Mitosis vs. Binary fission (bacteria)
Mitosis: very complex. Barring any errors, mitosis delivers an exact and equal amount of DNA to each new daughter cellBinary fission: circular DNA is copied and attached to the membrane. Cell splits, pulling the 2 copies apart and each new daughter cell gets one copy of the chromosome
Bacilli are ___ shaped bacteriaCocci are ___ shaped bacteriaSpirilla are ___ shaped bacteria
What is Tubulin?
- a globular protein that polymerizes to form MICROTUBULES
Aerobic leads to complete ____ of respiratory materialproduces ___ ATP per ___
complete oxidation of respiratory materialproduces 38 ATP per glucose
Origin of replication
is the location on the chromosome where replication begins
What fills the gaps made when RNase H removes the RNA primers?
According to the H-W, what are the 5 conditions that will ensure evolution doesnt happen?
1) Large population2) no mutation3) no immigration or emigration4) random mating5) no natural selection
Hardy-Weinberg Equilibrium states that…
allele and genotype frequencies in a population will remain constant from generation to generation in the absence of evolutionary forces
region of the chromosome that joins the sister chromatids
Mechanisms of DNA Repair: Base excision
the base portion ONLY is removed, first via a DNA glycosylase.other enzymes remove sugar-phosphate backbone, then DNA poly and ligase repair the NT
Define nondisjunction. What does it result in? What’s a real-life example of this?
when chromosomes fail to separate properly during anaphaseresults in uneven # chromosomes–either monosomy (missing chromo) or trisomy (extra chromo) ex of trisomy: Down’s
Name the 3 causes of DNA damage
1) Spontaneous hydrolysis2) Damage by external chemicals or radiation3) mismatched Base pairs
an enzyme that adds length to the telomeres
Binary Fission (bacteria): remember that prokaryotes contain?
extrachromosomal DNA (plasmids)There’s no system for segregating this DNA, so each daughter cell may or may not get certain plasmids based solely on random chance
When (at what phase of what) does crossing-over occur?
occurs during prophase of meiosis I
What phase? mitosis or meiosis? I or II? tetrads (“4”) are visible paired up with e/o as nuclear membrane dissolves
prophase of meiosis I
What role does cholesterol play?
Adds rigidity and fluidity to the membrane
Define: Intermediate Filaments (IMFs)
Several proteins that polymerize to form filaments that are:
- INTERMEDIATE in diameter b/t:
- microfilaments (smallest)
- microtubules (largest)
Diploid cell has __ chromosomes
G protein cascade: What activates protein kinase A (PKA)?What does PKA do?
-cAMP-PKA phosphorylates proteins, usually enzymesBOOM! Cascades
Remember that all bacteria are ______
Why is G0 phase of interest in the MCAT?
-b/c fully-differentiated neurons & cardiac muscle cells are frozen in G0 and do not divide-Multi-nucleated skeletal muscle cells are also in G0
DNA replication: What is the helicase?
it unzips the double-helix
uncontrolled cell division due to failure of cell’s normal regulatory patterns
Tools scientists use to determine taxonomy (5)
1) embryology- often two organisms have similarities that are only present during embryological development 2) Phylogeny- a shared evolutionary history can reveal similarities3) Anatomy4) DNA sequencing 5) Fossils- can reveal traits that were once shared but have since been lost
Sex-linked chromosomes: male=?female=?
male=Xfemale=Y(draw a punnett square)
name the Mechanisms of DNA repair (4)
1) proofreading2) mismatch repair system3) base excision4) NT excision
Phases of Mitosis: Anaphase
here, chromosomes separate and migrate towards the opposite ends of the cell
Methods of cell communication (6)
1) Endocrine2) Paracrine3) Autocrine4) Intracrine5) Juxtacrine6) Nervous System
What are Cilia?
protrusions found in:
- the lumen-facing side of EPITHELIAL cells lining various cavities in the body
Typical phenotypic ratio for a dihybrid cross
-long sections of repetitive DNA NT’s found at both ends of each chromosome-provide a buffer regions of non-coding DNA so that the repetitive losses in length don’t impact the gene sequence
When forming PHOSPHOLIPIDS, how does the reaction work?
- What does the glycerol do to the FA?
- What happens as a result?
- What NEW thing is formed?
FA is a long chain carboxylic acid
- one of the OH groups on the glycerol attacks the carbonyl carbon
- kicking off a H20 molecule
- & forming a new ester group
- kicking off a H20 molecule
Eastern Blot defwhat do probes bind to?
used to verify post-translational modification-probes bind to lipids, carbohydrates, or phosphates (the 3 most common post translational modifications)
includes skeletal, smooth or cardiac muscles found anywhere in the body
G protein cascade: alpha subunit does what?
binds both GTP and GDP
Phases of Mitosis: Telophase
here, nuclear membranes begin to re-form and chromosomes unwind
What’s the difference b/t:
Eukaryotic vs Prokaryotic Flagella?
- whipping motion
- made of tubulin
- spinning/rotating motion
- simple helices
- made of flagellin
Fungal reproduction (4)
-fungi spend the majority of their life as a haploid (have a single set of unpaired chromosomes)-fungi grow via long, intertwining branches called hyphae (which are haploid)-Yeasts reproduce almost exclusively by budding-Most fungi can reproduce both sexually (what life is hard…stress, little food, etc) or asexually (when life is good)
Tissue types (4)
1) epithelial2) nervous3) connective4) muscle
How many chromosomes do humans have…before replication?
Semi-discontinuous (DNA rep)?
refers to fact that one strand (leading strand) is synthesized continuously, which the other strand (lagging) is synthesized in okazaki frags (is discontinuous)
Gene regulation: rate of transcription
RNA has a short half-life, so gene products will only continue to be expressed if DNA is continually transcribed
What stage? Mitosis or meiosis? I or II?chromosomes condensed, but not paired
prophase of mitosis
G protein cascade: Alpha subunit does what?
-binds both GTP and GDP-activates cAMP (which converts ATP to ADP + 2Pi)
Pinocytosis is non-____, whereas phagocytosis is always ___-mediated
Fungi (3 examples)
mushrooms, yeasts, and molds
How do lysosomes FORM?
by budding off from the Golgi
Meiosis I takes a cell with __ homologous chromosomes (or__ totoal chromosomes) and creates?
23 homologous chromosomes, or 46 total chromosomescreates 2 cells, each with 23 non-paired, non-homologous chromosomes
- Starts where and
- Continues on to where?
Give 2 examples of PTM’s
- Starts in RER
- continues on to Golgi
ex: disulfide bonds, glycosylation
- Describe the LAC OPERON
- What does it regulate?
- What does the thing it regulates DO?
- What does it regulate?
Regulates EXPRESSION and TRANSLATION of LACTASE in bacteria (E. coli)
- Lactase is the enzyme that digests lactose
- Bacteria do much more anaerobic respiration (fermentation⇒lactose)
- so they will have a MUCH larger problem if lactose starts building up than if it were to happen in humans
Cell Cycle: M phase
mitosis happens during this phase
Mendel’s Laws: Law of Segregation
alleles segregate independently of one another when forming gametes
Describe the CENTROSOME (3 things)
- Is an amorphous area of proteins which contain CENTRIOLES
- Plays a role in APOPTOSIS (cell death)
capable of fixing CO2, and can therefore use CO2 as their carbon source for synthesizing organic molecules
- part of cytoskeleton
- also forms the “thin filament” portion of sarcomere
more concentrated than the cell, driving water to LEAVE the cellSHRINKS!
symbiosis where one participant benefits at the expense of the other (other participant IS harmed!)
Typical phenotypic ratio for a monohybrid cross
tunnels b/t adjacent cells, which allow exchange
Molecular cloning: recognition sequence
is the specific base sequence recognized by the endonuclease
Lichen: symbiosis b/t what?
b/t fungi and algae
Stages of Anaerobic respiration (3)?This is the same as in what else?
glycolysiskrebs cycleETC (same as in aerobic respiration)
G protein cascade: How do you shut down the cascade? (one way)
-Beta & gamma subunits re-bind with alpha subunit, deactivating it
STRONGEST of cellular junctions-they weld cells together, protecting against stress-are NOT watertight (only tight junctions are)
form the linings of the outside of the body, as well as various cavities INside the body. if it is lining a cavity or separating the body from the external environment, consider it to be epithelial tissue
When DNA is replicated, the ____ ___ does NOT change—you just end up with twice as much ___ per ___
chromosome number doesnt changetwice as much DNA per chromosome
Phases of Mitosis: Metaphase
here, chromosomes line up at the metaphase plate and form the spindle apparatus
Chromosomal Mutations: (4)
-duplications (non-disjunction)-deletions (non-disjunction)-translocations-inversions
-an ampiphatic molecule with a steroid region and a polar region-inserted in b/t phospholipids in high s in euk. cells
Molecular cloning: restriction nucleases
enzymes that cut DNA at specific pre-determined sequences
any change in the DNA sequence
What makes CILIA different from FLAGELLA?
Cilia are NOT used for locomotion of the cell itself
- Cell is fixed in place
- Cilia creates a beating pattern
- that moves fluid and other things PAST the cell
ATCGWhich are purines & which are pyridines?
GA= purines (General Authorities are pure)CT= pyrimidines
- VARIANCE from expected ratios, or
- RANDOM ASSORTMENT
What does REVERSE TRANSCRIPTASE do?
- What “idea”does reverse transcriptaseVIOLATE?
- Found in Retroviruses
- Translates its RNA nucleotide sequence into DNA
- because RNA wasnt able to be inserted into the host’s genome
VIOLATES THE CENTRAL DOGMA OF MMBio:
The “central dogma” of molecular biology describes the flow of genetic information in cells from:
- It states that genes specify the sequence of mRNA molecules
- which in turn specify the sequence of proteins
Cell Communication: Nervous system*this method often involves what?
Communication b/t cells via electrical potentials carried on neurons*these often involve cascades, too. Neurotransmitters bind to receptors on post-synaptic membrane, which initiates a signal
-type of endocytosis-refers to invagination of very large particles, bacteria, etc-only happens in a few types of cells
all fungi are heterotrophs. Most are saprophytic (live off dead, decaying matter), but a few are parasitic (live off live host, killing it), or mutualistic (symbiotic relationship)
Molecular cloning: hybridization means what?
means to join together to form a single strand
Genetic probabilities: “EITHER/OR”
If EITHER event occurring fulfills the requirement, add the probabilities of each event occurring individually
How many chromosomes do humans have…after replication
neurons of central & peripheral nervous systems
- Each time a DNA strand is replicated, the new strand is always slightly ____ that the parent strand
- Why is this?
- b/c DNA polymerases need an existing 3’ OH group
to add their first NT to
- they can’t replace that section of primer
What is CHROMATIN?
- what’s an example of something made of chromatin?
- general term for “DNA+protein”
CHROMOSOMES are made of chromatin
Cell Cycle: interphase
entire period OUTSIDE of mitosis
Lytic (cycle of) viral reproduction
-period during which viral genes are actively being transcribed and new viruses are being assembled. -During this phase, infected cells BURST!! to release large #’s of new viruses
G protein cascade: GDP is bound when protein is ___GTP is bound when protein is ___
is rRNA an enzyme?
Not by itself, but when it assembles into a ribosome it can
Where are all of the places Microtubules could be found?
HINT: Where there’s Cilia, there are MT’s
(^^Theres a few other places you’d find MT’s too^^)
- The 3 places cilia are
- ependymal cells
- uterine cells
- In the flagella of sperm
- In ALL cells
- as part of the cytoskeleton & spindle apparatus
What are Flagella?
- What are they used for?
- What are the ONLY cells that have flagella?
- whip-like projections from the cell body
- used for locomotion
- Human sperm cells are the only cells that have flagella
When is the only time chromosome number changes? (2)
1)during meiosis2) after fusion of gametes in the production of a zygote
G protein cascade
- G protein is made up of what 3 subunits?
Making genetic predictions for Dihybrid crosses–in the SAME individual
-Draw out 2 punnett squares (one for each trait) -To calc probability of 2 traits in the same individual, multiply the individual probabilities of each trait
(ribosomal RNA)is the polymer of which ribosomes are constructed
- Describe Activators & Repressors
Give an example of both, using the Lac Operon as a scenario
Regulatory molecules can either:
1) UPregulate DNA transcription
* ex: lactose in the lac operon
2) DOWNregulate transcription
* ex: glucose in lac operon
Major purpose of chromosomes is to…?
efficiently package the SUPER LONG DNA strands, so they can easily be stored b/t divisions and moved during division
- Define a Microtubule
- one of 3 parts of cytoskeleton of cell
- Made up of 13 protofilaments
- which are made when ß and α-tubulin form a heterodimer
Cell Cycle: G0
-cells that enter this phase become non proliferative-basically, there arent actively dividing (and may not in the future)-Many full-differentiated Eukaryotic NEURONS remain in this phase indefinitely
What stage? Mitosis or meiosis? I or II?Tetrads line up IN PAIRS at metaphase plate
metaphase of meiosis I
where a cell takes up small particles by lumping into the plasma membrane, forming a vesicle called an endosome
Second messenger systems
-water-soluble hormones or signaling molecules bind to mem receptors on external surface of plasma membrane-this binding rarely stimulates immediate response from cell–more often it initiates a cascade that increases size of signal, which eventually stimulates cellular response
What would happen if crossing over didn’t occur?
All of the genes on one chromosome would always demonstrate linkageLOSS OF GENETIC VARIATION! WHICH IS BAD!
name the 3 components of NT’s
1) triphosphate2) sugar3) base (one of four: ATCG)
for RNA sequences
Prokaryotes vs Eukaryotes differences
Pro: have no nucleus, no membrane-bound organelles, they have circular DNA, no histones or chromosome struc, and 70S(50S & 30S) ribosomesEuk: have a nucleus, mem-bound organelles, linear DNA with histones * chromosome struc, and 80S(60S and 40S) ribosomes
- lipid molecules with a non-polar tail*
- and a polar phosphate head*
- Make up a bilayer of a cell membrane
Genes are regulated via 3 basic mechanisms. name them.
1) rate of transcription2) Activators and repressors3) permanent or semi-permanent suppression
If a male with a sex-linked recessive disease has children with a normal woman, ?
All of his daughters (XX) will be carriers
Adenine (A), pairs with?
T via 2 hydrogen bonds
- An individual who carries two identical copies of the recessive gene is…?
________s are a very common second messenger system that the MCAT loves to question you on
Gram Positive vs Gram Negative: describe gram (+)
Gram Positive: -stain purple-very thick cell wall-form endosomes-Single cell membrane
In humans, cilia are found exclusively in what 3 SYSTEMS?
- Respiratory system
- Nervous system
- ependymal cells
- Reproductive system
- uterine tubes
- What are its 3 main jobs?
- Organize proteins
- Continue post-translational modification
- Excrete proteins in vesicles bound for:
- Plasma membrane
- organelles, or
- BACK to the ER (retrograde transport)
Types of membrane transport (4)
1) simple diffusion: no ATP req’d2) facilitated diffusion: No ATP req’d (ex: osmosis)3) active transport: ATP req’d4) Secondary active transport: no DIRECT coupling of ATP req’d
Anaerobic respiration occurs mostly in?
Anaphase is indicated by:
- separation of the chromosomes and
- migration toward the opposite poles of the cell
Define: transport proteins
Integral proteins that span entire width of bi-laye
Create tunnels for the passage of:
- proteins, or
- other substances
…through the hydrophobic core
Compare metaphase for meiosis I and metaphase
meiosis I: tetrads line up IN PAIRS at the metaphase platemitosis: tetrads line up SINGLE-FILE at metaphase plate
How are PHOSPHOLIPIDS formed?
- What 3 things do you COMBINE?
Cell Communication: Juxtacrine
signaling req’s direct contact b/t two cells
Crossing over happens to such an extent that two genes must…?
be VERY close to e/o on the chromosome to NOT assort independently (aka linkage…which is bad)
Differentiate b/t aerobic & anaerobic respiration
aerobic uses oxygenanaerobic doesnt use oxygen–DOES use an ETC, but doesnt use O2 as the e’ acceptors
bone, cartilage, blood, lymphatic tissue, fat, etc. basically, if a cell is obviously not epithelial, nervous, or muscle, it’s probably connective
The Smooth ER is the site of?
Site of lipid synthesis/modification
(but NOT the site of lipid metabolism!)
Mycorrhizae: symbiosis b/t what?
b/t fungi and plant roots
- Bacterial colonies grow ________,
_____ each generation
- Wrt Bacterial growth, there is a LIMIT to what?
- Why is this limited?
- Bacterial colonies grow EXPONENTIALLY
- doubling each generation
HOWEVER, there is a LIMIT to colony size!
- This is because:
- Food and resources decrease, and
- Waste accumulates
What happens to cholesterol in the cell membrane at higher temperatues?
non-polar region of CHO interacts with hydrophobic tails of lipids, holding them in place and this adding RIGIDITY
G protein cascade: what causes conformational change that activates cytosolic domain of an integral protein?
when a hormone or signal molecule binds to the GPCR
Cell Cycle: S phase
DNA replicated here
Mendel’s Laws: Law of Independent association
genes located on different chromosomes assort independently
Function of glomerulus
capillary bed that strains the blood-allows fluids, ions, & molecules around the size of GLUCOSE (or smaller) to pass through Bowman’s capsule-anything bigger will remain in the capillaries and exit via the efferent arteriole, which eventually empties into the renal vein
- Describe TIGHT Junctions
are water-proof barriers
ALL proteins bound for cytosol
plus SOME proteins bound for other organelles
are made on ?
Free-floating RIBOSOMES in the cytosol
haploid cell has __ chromosomes
n for humans, n=23
LESS concentrated than the cell
- driving water to ENTER the cell
- it might BURST!
verify presence of DNA sequencesalso indicates relative size of restriction fragments
____ is ALWAYS req’d to move something against its  gradient or against an electrical potential
- Explain the GRADIENT across inner mitochondrial membrane
- What happens if you were to insert H+ channels within the membrane?
intermembrane space has higher hydrogen ion [H+] concentration, so it is more acidic
- adding H+ channels would give H+ ions an ALTERNATE pathway back into the matrix OTHER than going solely via the ATP synthase
- as a consequence, ATP production would decrease
What happens to cholesterol in the cell membrane at lower temperatures?
At LOWER temps:
- Non-polar tails of lipids could interact and cause crystallization
- WHICH IS BAD
- The rigid steroid portion of CHO disrupts VDW forces between lipid tails tails
- which maintains (just enough) FLUIDITY
p^2+2pq+q^2=1p+q=1What do p, q, p^2, and q^2 represent?
p & q refer to % of each ALLELE present as a fraction of all the alleles in the population-p^2 represents fraction of INDIVIDUALS who have homozygous dominant genotype (TT)-q^2 represents faction of individuals with the heterozygous genotype (tt) ***in short: p and q represent fractions of p and q ALLELES in the population***q^2, 2pq, and q^2 represent fractions of INDIVIDUALS with each possible genotype
What cellular junction is the STRONGEST of the four?Where might you find this type, and why?
Desmosomesfound in tissues that receive high amounts of shear stress, like the epidermis
DNA replication: RNase H
removes all RNA primers
Cytosine (C), pairs with?
G via 3 hydrogen bonds
Semi-conservative (DNA rep)?
refers to fact that each of newly formed daughter helices is made up of one OLD strand plus one NEW strand
viruses that infect bacteria-have a capsid head, tail, tail fibers, etc.(typical virus looking thingy!)
Many enzymes are activated by?
Genetics: How to make predictions. What should you always do FIRST?
Draw a punnett square
Where are steroid membrane receptors located? Why?
in the nucleusbecause steroids can diffuse through the hydrophobic membrane core (dont need a transport protein)
“-tase” means it is?
an ATP-requiring enzyme!!!
Compare PROPHASE for:
- meiosis I and mitosis
- Tetrads are visible paired up with e/o as nuclear membrane dissolves
- Chromosomes ARE condensed, but ARENT paired
Vaccine definition & why do vaccines become less effective with time?
-is an inactive portion of a virus delivered to a person so their immune system can develop antibodies against the virus, without actually being infected by it-they become less effective b/c of SUPER FAST viral mutations!
Thymine (T), pairs with?
A via 2 hydrogen bonds
Function of proximal convoluted tubule (PCT)
-section of nephron b/t bowman’s capsule & descending limb of the loop of henle-along PCT Na+ is reabsorbed via active transport & glucose is reabsorbed via secondary active transport-since water and solutes are reabsorbed in the same ratio, the filtrate remains ISOTONIC
Cell Cycle: G2
comes after S. -cell continues to grow & has high metabolic activity (esp. production of microtubules in preparation for mitosis)
Taxonomy”Do Kings Play Chess On Fridays, Generally Speaking?
What will you assume if you’re asked to predict the genotype of offspring when you are NOT given info on ONE of the parents?
assume the other parent is NOT affected, thus NOT a carrier of whatever
MYOSIN is a ___, not a ___
NOT a microfilament!!
What 2 things exhibit the 9+2 arrangement?
Cilia & flagella
Cell Communication: Autocrine
signal molecules secreted by a cell bind to receptors ON THAT SAME CELL
“The Species Distinction”
organisms classified as different species should not be able to mate with one another and produce viable, fertile offspring
What is the 9+2 format?
- NINE doublets (2 microtubules each) surrounding a CENTER doublet (2 microtubules) in a wheel-like design
Total of 20 microtubules (18+2)
- Each of these microtubules are made up of 13 protofilaments
- What are the 6 possible destinations for ALL proteins?
- Where are all these proteins made?
- Plasma Membrane
- Extracellular secretion
made in: RER
What are some things that trigger cell apoptosis? (4)What’s something else apoptosis does apart from removing bad cells?
extreme heatradiationviral infectionDNA damage, etcCan also remove healthy, but unwanted cells
Define Western Blot
- Are used for segments of ______?
- What are used as probes?
HINT: W-e-s-t-e-r-n has 7 letters, as does the thing it sequences….
- is for PROTEIN segments
- instead of NT segments
- Radioactive antibodies are used as probes
- instead of NT sequences being used as probes
Gram Positive vs Gram negative: describe gram (-)
-stain pink-relatively thin cell wall-do NOT form endosomes-contain 2 cell membranes: one inside the cell wall and one outside the cell wall
vesicle on inside of membrane fuses with plasma membrane & dumps its contents into extracellular space
Define: Thin filaments of the sarcomere
- Formed from microfilaments
Thin filaments act as a TRACK along which THICK FILAMENTS move during contraction
GLIAL CELLS, such as:
- Schwann cells
- Ependymal cells
are also considered to be what?
- Also! Remember that EPENDYMAL cells contain…?
EPENDYMAL cells contain CILIA!
Making genetic predictions for dihybrid crosses– “for __ # of individuals” w/ a phenotype or genotype
-If # of individuals with a specific genotype or phenotype is asked for, multiply the total probability of having BOTH traits by the total number of offspring
4 genetically distinct HAPLOID daughter cellsCentromeres do NOT split during meiosis I, but do during meiosis II
- In order for natural selection to occur, what 2 things must happen?
HINT: Polymorphisms (discontinuous genetic variation)
1) An individual MUST have a polymorphism that provides an evolutionary fitness advantage
2) This advantage MUST result in the individual with the favored polymorphism
…differentially** **producing MORE offspring!
- its good to be different!
- Give a species resistance against illness & stuff
Cell Communication: Paracrine (plus example)
signal molecules secreted by one cell bind to receptors on other cells in the local area. ex: neurotransmitters acting in the synaptic gap
How many chromosomes in a haploid cell?
Molecular cloning: gel electrophoresis
lab technique used to separate molecules by size
Gene Regualtion: permanent or semi-permanent suppression
Methylation or other covalent modification that prevents or dramatically DECREASES transcription
What are Thick filaments made of?
What do they move along, and during what?
- Made up of MYOSIN (motor proteins)
- move along thin filaments
- during contraction
Lysogenic (cycle of) viral reproductionexample?
-is the dormant cycle of the virus during which time viral DNA is incorporated into the host’s genome, but new viruses are not being assembled. ex: HIV infection without having AIDS symptoms
oxidize organic or inorganic cpds to harvest energy
Phases of Mitosis: prophase
nuclear membrane dissolves and chromosomes condense
Do mitochondria use the same genetic code to translate their DNA?
Genetics: what is assumed for an individual with the DOMINANT phenotype?
Anaerobic respiration takes place where? (2)
Cytoplasm & mitochondria
Do all human traits follow the Mendelian pattern?
NOPE! Most dont, actually.
“Wild Type” =?
the normal or typical phenotype
2 genetically IDENTICAL diploid daughter cells, which are genetically IDENTICAL to the mother cell that produced them*The centromeres split*
proteins around which DNA helix is wrapped when condensed into chromosomes
DNA replication: DNA polymerase reads in _____ direction, thus builds new strands in the ___ direction
3’ to 5’ builds new strands in 5’ to 3’ direction
Define a Membrane receptor
any protein that specifically binds to a signaling molecule (ligand)
- …and initiates a cellular response
DNA replication is: (3) name the traits
“-ase” means it is ?
Guanine (G), pairs with?
C via 3 hydrogen bonds
DNA replication: What does the primase (which is an ___) do?
(which is an RNA polymerase)constructs short RNA primers on both strands
form of symbiosis where both parties benefit equally
set of 8 histone proteins in a cube shape with DNA coiled around it.
Microfilaments are made up of ___ subunits
Genetic probabilities: “BOTH/AND”
if both events occur simultaneously, multiply probabilities of each event occurring individually
What besides DNA and RNA are nucleotides present in?
Telomerase & ribosomes have bits of attached RNAATP has NT’s too
Define: Surface (“Peripheral”) proteins
- Where are they ENTIRELY contained/found?
- Proteins on a cell membrane that DONT enter into hydrophobic core*
- contained entirely on polar surface of membrane
How much synthesis of lac mRNA can you expect if:
- You have BOTH lactose (activator) AND glucose (repressor) present
- Since Glucose IS present, you’ll have low cAMP*
- cAMP unable to bind & activate CAP, which is unable to help RNA Poly bind to the Promoter region*
Since RNA Poly is LESS LIKELY to bind to promoter region:
- you’ll have VERY LITTLE lac mRNA synthesized
How much synthesis of lac mRNA can you expect if:
- Lactose (activator) is PRESENT, and Glucose (Repressor) is SCARCE?
- Since glucose is SCARCE,*
- cAMP IS able to bind to CAP*
- This enables RNA Poly to easily bind to the PROMOTER region
=HIGH LEVELS of lac-mRNA synthesis
- Takes a cell with __ pairs of _________ chromosomes (or __ total chromosomes)
- …and creates _ ____
- Each with __ non-_____ed, non-_________ chromosomes
- Takes a cell with 23 pairs of homologous chromosomes, or 46 total chromosomes
- and creates two cells
- each with 23 non-paired, non-homologous chromosomes
Generally speaking, chromosomes tend to ______ in size throughout the cell cycle
In Meiosis I, You start with 23 homologous chromosomes
- Which of those 23 chromosomes will be the LARGEST?
1 >>> 23
Chromosome ONE is BY FAR the LARGEST chromosome! (Always!)
During cell division, are chromosomes DUPLICATED?
- How do levels of DNA and Chromosomes vary during cell division?
- Chromosomes are NEVER“duplicated”*
- in number during cell division*
They are “REPLICATED”
- meaning each single chromosome gains an identical sister chromatid
- …but only the amount of DNA has INCREASED*
- …the # of chromosomes has NOT!!!*
- Before DNA replication each cell will have 46 chromosomes
- Afterward each cell will still have ONLY 46 chromosomes
Which of the following statements is/are TRUE regarding human chromosomes?
I. In their condensed form they contain a large amount of protein
II. They are in their condensed form for the majority of the cell cycle
III. They contain nucleosomes
IV. There are 46 non-identical chromosomes in each somatic cell
- A. II and IV
- B. I and III
- C. I, II and III
- D. I, III and I
Statement I is true
- Chromosomes contain many histones
- which are a type of protein
Statement II is false
- During most of the cell cycle the chromosomes are unwound
- Not until prophase do the chromosomes condense
Statement III is also true
- A nucleosome is a set of four histones wound together
Statement IV is true
- You may be tempted here to think that we only have 23 pairs of non-identical chromosomes because of the existence of homologues
- That would be true IF homologues were identical
- However, homologues are definitely non-identical because they contain a random assortment of alleles
What is a PROTEIN that is very abundant in CHROMOSOMES?
- HINT: Chromosomes package DNA…..
During most of the cell cycle, CHROMOSOMES are wound/unwound?
- It’s not until _____ that the chromosomes _____
- During most of the cell cycle,*
- chromosomes are UNWOUND*
Not until PROPHASE do the chromosomes CONDENSE
Define a NUCLEOSOME
- Where could you find them?
a nucleosome is a set of four histones wound together
- Found in CHROMOSOMES!
- Chromosomes package DNA*
- Where there’s DNA, there Histones, & where there’s Histones there’s Nucleosomes*
There are ALWAYS __ chromosomes in a somatic cell before, during, and after MITOSIS
Uptake of glucose from the gut and transport of K+ ions through the voltage-gated channels of a neuron are best described as:
- A. secondary active transport and active transport, respectively
- B. active transport and facilitated diffusion, respectively
- C. secondary active transport and facilitated diffusion, respectively
- D. active transport and diffusion, respectively
Uptake of glucose at both the gut and the kidney is accomplished via a secondary active transport system–
Meaning that a “secondary” molecule is actually the one actively transported
- in order to get the molecule of interest into or out of the cell
In this case, sodium is transported against its gradient
- where it pairs with glucose
- and brings it back into the cell
- back down sodium’s gradient
- and brings it back into the cell
The flow of K+ ions thru a potassium channel in the neuron does NOT involve ATP,
- and is thus REGULAR diffusion
- However, because it goes thru a CHANNEL PROTEIN, it is considered “facilitated diffusion”*
Which of the following is NOT a function of the endoplasmic reticulum?
- A. detoxification of cellular chemicals
- B. lipid production and metabolism
- C. synthesis site of extracellular proteins
- D. post-translational modification of proteins
The ER, between the smooth and rough sections, is responsible for:
- Detoxifying chemicals
- producing lipids
- synthesizing extracellular proteins
- modifying translated proteins
- and various other functions
The key here is that lipids are
MADE at the smooth ER…
…but are METABOLIZED in the
Thus B is a false statement and is the correct answer
DESMOSOMES are found in tissues that receive a lot of ____ and ____, such as _______ cells
REMEMBER: Desmosomes are the strongest of the 4 cell junction types
Desmosomes are found in tissues that receive a lot of PRESSURE and IMPACT
- such as epithelial cells
Describe SUBSTRATE-LEVEL PHOSPHORYLATION
- Where’s one place this happens?
is a type of metabolic reaction that results in the formation of ATP or GTP by:
- the DIRECT TRANSFER of a PHOSPHORYL GROUP(PO3)
- ….to ADP or GDP
- from a phosphorylated reactive intermediate
- This happens in the KREBS CYCLE!*
- GDP is phosphorylated into GTP*
What is it that INTRONS are spliced out of?
Introns are removed from pre-mRNA
(NOT replicated DNA!)
- The DNA strand shown below is from the CODING (!) strand of a section of human DNA*
- Which of the following gives the matching pre-mRNA sequence?*
- A. 5’UAAGC3’
- B. 3’UAAGC5’
- C. 3’GCUUA5’
- D. 3’AUUCG5’
- To answer this correctly, you must differentiate “coding strand” from “template strand.”
The template strand is the one copied
The coding strand is the other strand
- the complement to the template strand
- which is NOT copied
As a result, the:
- new DNA strand OR
- the new pre-mRNA strand
- will be an EXACT COPY of the coding strand*
- (EXCEPT, in the case of pre-mRNA, T will be replaced with U)*
- The next skill you need is to keep careful track of the 3’ and 5’ ends
- Normally, we need the strands to run in opposite directions
- (so if the template strand was listed 5’ to 3’ the new strand would consist of the matching base pairs running 3’ to 5’)
However, note that here you are NOT given the template strand, but the coding strand
Thus, the coding strand and the new pre-mRNA strand will both run the same direction and will be identical
- except for replacing T with U
- GENES can only produce WHAT?
- You cannot have a gene transcribed, and then translated into a _____, a ___, or anything else.
Genes can ONLY produce PROTEINS!
DON’T FORGET THIS!
- You cannot have a gene transcribed and then translated into a carbohydrate, a fat, or anything else
Hormone Q⇒ Receptor P ⇒activates adenyl cyclase ⇒converts ATP to cAMP ⇒leads to phosporylation of Protein Z, which actively transports Glucose into cell
If you needed to QUICKLY remove Glucose from the cell, inhibiting which of the above things would do it FASTEST? Why?
- Stopping the final step in the chain
- In this case, it will not matter what previous molecules are still present
If you were to remove all of Hormone Q, for example, you’d still have to wait for whatever was there right BEFORE removing it to make its way through the cascade
LYSOGENIC vs. LYTIC
Which is the “DORMANT” cycle?
Will it always be dormant?
- It is inevitable that at some future time, usually during a time of stress, the virus WILL become “lytic”
- and commandeer the host’s machinery to actively produce virions
- They have cell walls containing _____
- They are _____ during most of their life cycle
- They ____ food before _____ing it
- They are capable of both _____ and _____ reproduction
- They have cell walls containing CHITIN
- They are HAPLOID during most of their life cycle
- They DIGEST food before INGESTing it
- They are capable of both SEXUAL and ASEXUAL reproduction
What are 4 characteristics about the NUCLEUS?
- Where DNA is
- DNA cannot leave nuleus
- Is by a dual bi-layer membrane
- one bi layer is continuous with ER
- contains nuclear pores
Non-nuclear DNA is found where?
- the nuclear membrane dissolves
- the chromosomes condense
What are the 2 HARDY-WEINBERG Formulas we need to know?
Tissue organization: ___>___>___>___
The intermembrane space has a ___er pH than the matrix
- Therefore, the intermembrane space is more ____
lower pH than matrix
intermembrane space is more acidic