MGC Biology

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What is a virus?: An infectious particle that contains nucleic acids.
- obligate intracellular parasite
- not living ("live" characteristics inside a host)
- tiny
- infectious
genetic material incapsulated in a protein coat
- could or couldn't have an envolope (if it doesn't it's naked)
infection is highly specific => called attachment/adsorption
- injects int's genetic material into the host => called eclipse/penetration
* Bacteriophate: a phage (virus) that infects a bacterium.
Is a virus an obligate intracellular parasite?: Yes.
Is the infection of a virus highly specific? What is this called?: Yes, its called attachment/adsorption.
Do viruses have to have an envolope?: No, not all viruses need to have an envelope. If it doesn't it's naked.
What is the viral life cycle:: Lytic, lysogenic, productive
What is it called when viruses inject it's genetic material into the host?: eclipse/penetration
What are the steps in the lytic cycle?: 1. Virus binds host and injects its genetic material.
- only genome enters
protein coat outside floats away (that's why its called eclipse)
2. Phage enzymes chop up host genome for spare parts => get nucleotides
3. Viral replication and assembly
4. Cell lysis (b/c of lysosomes)
What are the steps of the lysogenic cycle?: 1. Virus binds , injects genetic material.
2. Genetic material integrates into host genome (now called "prophage")
3. Viral genome replicated w/ host genome.
4. After stimulus (aka. stress), viral genome will excise itself (if improperly cut, can take host genome with it... this is called transduction)
5. replication with assembly
6. cell lysis
* Effect is must more magnified than the lytic cycle
What are the steps of the productive cycle?: 1. like lytic cycle except no cell lysis
2. instead buddying off of cell membrane ==> virus now has host's membrane (can help it infect)
* cell isn't destroyed.
Is the cell destroyed in the productive cycle?: No, it budds off of the cell membrane whcih can help it infect.
Can bacteriophage used productive cycle?: No, b/c bacteria have a cell wall.
What are the different types of viral genomes?: 1) + RNA virus (coding strand)
2) - RNA virus (template strand)
3) DS DNA virus
4) Retroviruses (RNA=>DNA... goes against central dogma)
What are the properties of the +RNA virus?: - Coding strand, so RNA injected can be directly translated (like mRNA).
- Ribosomes immediately starts.
- Must code for RNA dependent-RNA polymerase ==> RNA => RNA b/c host can't do it (so can send viruses out)
- Most use lytic cycle
What is the purpose of RNA dependent-RNA polymerase?: RNA => RNA b/c host can't do it.
What are the properties of the -RNA virus?: - template strand (need to get this into a coding strand)
- will code for coding strand which will then be used for translation.
- must carry an RNA-dpenedent RNA polymerase. (using coding strand to make viral genome)
- Most use lytic cycle.
Which viruses must carry/encode RNA dependent RNA polymerase? Be specific.: +RNA must code for RNA dependent RNA polymerase.
-RNA must carry an RNA dependent RNA polymerase.
What are the properties of DS DNA virses?: - larger genome
- must encode enzymes for DNA replication
- most use lysogenic cycle
What are the properties of retroviruses?: - RNA => DNA
- encodes for enzyme "reverse transcriptase"
- HIV: reverse transcriptase has no proofreading capabilities so what that means is you'll get a lot more mutations and therefore, harder to fight.
- +RNA virus that can undergo lysogency (integrates into host genome)
Does reverse trancriptase have proofreading capabilities?: reverse transcriptase has no proofreading capabilities so what that means is you'll get a lot more mutations and therefore, harder to fight.
What are the properties of prokaryotes?: - unicellular
- no organelles (everything happens in cytosol)
- some have flagella (corkscrews)
- cell walls.
- divide by binary fission => daughter cells are clones.
- genome is circular DS DNA
What is the genome is prokaryotes?: DS DNA
How do prokaryotes divide?: binary fission. (daughter cells are clones)
What are the structural classifciations of prokaryotes?: a) shape: cocci (sphere), bacilli (rod-shaped/oval), spirilli (spiral)
b) gram staining (+/-) for peptidoglycan layer (in cell wall)
How many membranes are there in gram+ and gram-; what makes gram "+" stain?: There are two membranes in gram -. One membrane in gram +. The peptidoglycan layer is much larger in gram+ stains and therefore, the stain is trapped there.
Classify the growth requirements of preferred living conditions.: 1) auto/heterotrophs (carbon source)
2) photo/chemotrophs (energy source)
3) can have problems:
- glucose- or fructose- => can't use these for carbon => if you put these in a dish and put glucose in, doesn't do anything.
- His-, Trp-, Amino Acid- => can't make them and therefore need to put these aa's in the media for them to survive.
Classify the temperatures of the preferred living conditions.: - psychophiles (peak reproductive rate at 0deg C)
- mesophiles (peak reproductive rate at ~30deg C ==> this will affect humans the most)
- thermophiles (peak reprod rate >45 deg C)
Classify the oxygen tolerance of preferred living conditions.: i. aerobic => require O2
ii) anaerobic
- facultative => prefers O2, not required
- tolerant => doesn't use O2 but can live in it
- Obligate => dies in oxygen
What is binary fission?: - results in daughter cells that are clones.
- asexual reproduction (sucks b/c you don't get genetic diversity but you do get:)
- exponential growth
- lag phase, log phase, stationary phase
What are the bacterial genetics (3)?: transduction, transformation, conjugation
Transduction: improper excision of prophage => part of host genome travels with it.
transformation: bacteria taking up DNA from environment
Conjugation: - genetic material is transferred thru sex pilus
- F-factor (fertility) => codes for sex pilus
- if bacteria have it => called F+, if not, F-
- can transfer genetic material from F+ to F-... aftewards, F- is now F+.
Where is F+ factor?: F factor is in plasmid
Where is Hfr factor?: Its incorporated into bacterial genome.
nucleolus: a region within the nucleus where rRNA is transcribe and ribosomes are partially assembled
rRNA: Ribosomal RNA; the type of RNA that associates with ribosomal proteins to make a functional ribosome. It is thought that the rRNA has the peptidyl transferase activity.
Where in the cell would the M6P receptor be transcribed?: Transcription is the reading of genes in DNA by RNA polymerase to make mRNA. All transcription takes place in the nucleus.
Does endocytosis bring newly synthesized proteins into the lysosome?: No.
Endocytosis: The uptake of material into a cell, usually by invagination.
Where do trypsin and pancreatic lipase function? What are they?: They are secreted enzymes that function in the small intestine, not an acidic environment.
If a protein were synthesized without a signal peptide, in which cellular region would it reside in?: - The signal peptide is at the N-terminus, the first portion of a protein to be synthesized by the ribosome in the cytoplasm.
- In the presence of a signal peptide, the ribosome docks with the ER to complete translation.
- In the absence of a signal peptide, the protein is translated and resides in the cytoplasm.
ER lumen correpsonds most closley with which compartments?: The interior of the ER (the lumen) correspond to the interior of:
- the golgi
- the interior of secretory vesicles
- extracellular envrionemnt
What is the Krebs cycle?: The 3rd stage of cellular respiration, in which acetal-CoA is combined with oxaloacetate to form citric acid.
- The citric acid is then decarboxylated twice and isomerized to recreate oxaloacetate.
In the process, 3 molecules of NADH, 1 molecule of FADH2 and 1 molecule of GTP are formed.
What products are formed in Kreb's cycle?: Citric acid;
3 molecules of NADH
1 molecule of FADH2
1 molecule of GTP are formed
True or false: Steroids are hormones that are small and hydrophobic and can freely diffuse through the plasma membrane.: True.
Are lysosomes and peroxisomes in the secretory pathway?: No, lysosomes and peroxisomes are separate destinations that proteins can be targeted to but are not in the secretory path leading to the cellular exterior.
Which one is responsible for amoeboid motility: microtubules or microfilaments?: microfilaments
Which one is responsible for flagella: microtubules or microfilaments?: microtubules
Which one is responsible for organelle movement: microtubules or microfilaments?: microtubules
Which one is responsible for mitotic spindles: microtubules or microfilaments?: microtubules
What is endocytosis?: - the process by whcih the cell internalizes receptor-ligand complexes from the cell surface, such as polypeptide hormones bound to their receptor.
- At the cell surface, the receptor-ligand complexes cluster in clathrin-coated pits and pinch off the vesicles that join acidic cojmpartments known as endosomes.
paralysis of microtubule-based movement of flagellae and cilia would result in (T/F) and why: - male infertility - ectopic pregnancy in women - chronic lung infections - failure to ovulate in women: - male would be infertile due to immobile sperm.
- in females, ova wouldn't enter the Fallopian tubes normally due to the lack of cilia, causing increased risk of ectopic pregnancy.
- Lungs would require cilia to remove bacteria and other particulates.
- HOWEVER, ovulation is determiend by levels of circulating hormones and will not be affected by the lack of dynein.
What effects ovulation?: ovulation is determiend by levels of circulating hormones and will not be affected by the lack of dynein.
Hypertonic solution: extracellular environment has a higher solute concentration.
What is a codon: a segment of an mRNA molecule that codes for one amino acid in a polypeptide chain formed during protein synthesis.
What does operon regulate?: transcription
Do primary spermatocytes undergo mitosis?: NO, Primary spermatocytes undergo meisois to form secondary spermatocytes; NOT MITOSIS.
Does replication of chromosomes occur prior to the beginning of cell division with prophase?: Yes, replication of chromosomes occurs prior to the beginning of cell division with prophase.
Crossing over occurs btw paired homologues before they separate into two different nuclei during what?: meiosis; NOT mitosis.
Chloroplasts and mitochondria have their own what?: Chromosomes. The genome must replicate during G1 b/c this is when the organelles are produced. S phase is the time when cellular chromosomal material is replicated.
Sexual reproduction indicates what?: meiosis
DNA replication occurs in haploid cells => mitosis or meiosis: Mitosis.
Glucose is split into two 3-carbon molecules at the end of glycolysis called what?: Pyruvate.
What happens to each pyruvate at the end of glucose?: Each pyruvate forms one acetyl CoA so the net rxn per glucose must start with 2 acetyl CoA on the left side of the equation.
What does decarboxylation mean?: It means it closes a CO2.
Where are pyruvate dehydrogenase and the Krebs cycle located?: mitochondria.
Describe members of phylum Protozoa (protozoans): - unicellular eukaryotes
- mostly heterotrophic
- can reproduce either sexually or asexually.
What occurs when glycogen is broken down?: increase in glucose.
What does ACTH stimulate?: ACTH stimulates teh adrenal cortex to produce cortisol and aldosterone.
What does NADPH contain?: Ribose, a pentose.
How many rounds of cell division are in mitosis and meiosis?: Mitosis: 1
Meiosis: 2
What is the initial processes of embryonic development of females? (q#3 on pg 49): Oogenesis proceeds up to the formation of primary oocytes, which are arested in meiotic prophase I.
- They will remain arrested at this stage up until the time that they prepare for ovulation and complete meiosis I, including going through anaphase I, to form secondary oocytes which are ovulated.
Klinefelter's syndrome in whcih a male has an extra X chromosome (XXY), is the result of nondisjunction. The failure in spermatogenesis that could produce this would occur in? what stage: Anaphase I. X and Y would count as homologous chromosomes and so would normally separate during meiosis I. The separation occurs during anaphase, when chromosomes are drawn away from each other toward opposite sides of the two cells being formed.
During whcih of the following are cells with a single unreplciated copy of the genome formed in humans? a. interphase b. meiosis i c. meiosis ii d. mitosis: Primary oocytes are arrested in humans, the only cells that have a single copy of the genome are gametes, formed during meiosis. Cells have a single unreplicated copy of the genome after the second meiotic division.
In humans, the only cells that have a single copy of the genome are what?: gametes
What does the ectoderm form?: skin and the nervous system, including the brain
What does the mesoderm form?: muscles, blood, bone, reproductive organs, and kidneys
5' cap: - A methylated guanine nucleotide added to the 5' end of eukaryotic mRNA.
- The cap is necessary to iniciate translation of the mRNA.
A band: The band of the sarcomere that extends the full length of the thick filament. The A band includes regions of thick and thin filament overlap, as well as region of thick filament only. A bands alternate with I bands to give skeletal and cardiac muscle tissue a striated appearance. The A band doesn't shorten during muscle contraction.
Classify acyl-CoA => enoyl-CoA if on order to get it going, FAD needs to be turned into FADH2.: An enoyl consists of a carbonyl group plus a dbl bond btw the alpha and beta carbons. (Recall that the carbonyl carbon is #1; the next carbon, #2, is known as the alpha carbon; carbon #3 is the beta carbon) Creating a dbl dlb bond from a single bond is an oxidation. Also the reduction of FAD to FADH2 (gain of electrons) is a signal that the conversion of acyl-CoA to anoyl-CoA is an oxidation. Remember that oxidations are always accompanied by reductions.
Depriving a cell of oxidation would have what effect on the cycle of Beta-oxidation?: The electron transport chain and oxidative phoisphorylation normally use oxygen to oxidize NADH and FADH2, thereby regenerating NA and FAD. Without oxygen, NADH and FADH2 build up.
The enzyme responsible for the conversion of L-hydroxyacyl-CoA to ketoacyl-CoA is a...: dehydrogenase
- Conversion of an alcohol to a ketone is an oxidative remove of protons, a dehydration.
If the concentration of acetyl coA produced from fatty acid oxidation is very high, the citric acid cycle is overwhelmed and acetoacetate and other ketone bodies form. The reason this occurs is that...: insufficient oxaloacetate is present to combine with acetyl-CoA.
- under conditions of low carbohydrate availableility, OAA is used for gluconeogenesis. This lowers its availability to the citric acid cycle. An insufficient supply of OAA, which combined with acetyl-CoA at the begining of the citric acid cycle, prevents acetyl-CoA from being further oxidized.
True or false: Fatty acid oxidation and fatty acid biosynthesis pathways both use or produce acetyl-CoA.: True. Synthesis builds fatty acids out of acetyl-CoA two carbon units, while oxidation produces acetyl-CoA.
What effect would adding an anti-suybstrate antibody have on the empiriracal rxn kinetics of the enzyme and its substrate?: The antibody will bind to the substrate, which increases the apprent Km.
Bone resorption: Gradual loss of bone
Negative or positive feedback regulates thyroxine production? How is this done?: negative feedback;
- plasma thyroxine regulates thyroxine secretion through feedback regulation by the hypothalamus (TRH) and the anterior pituitary (TSH)
Thyroid hormone levels in the blood would be increased by which of the following? - elevated plasma CO2 - exposure to sever cold for a long period: people exposed to sever cold generally have elecated basal metabolism to generate increased heat, and thus have elevated levels of thyroxine.
- What do vaccines do? - What does this have to do with B cells?: - Vaccines provide protection by stimulating specific clones of immune cells that recognize antigen to proliferate.
- B cells which respond against a vaccine will proliferate and provide protection against future infection by the same virus.
Describe the Cell Theory: The cell theory states that all living things are composed of cells; cells are the basic functional unit of life; cells arise only from pre-existing cells; and cells carry their genetic information in the form of DNA.
What type of laboratory method can be used to separate cells without destroying them?: Low speed centrifugation can separate cells on teh basis of type without destroying them.
(T/F) Differential centrifugation can be used to separate cell structures with similar densities.: False, different densities are required for separation.
Name the two distinct groups into which all cells can be categorized.: All cells can be categorized as either prokaryotes or eukaryotes.
What is the key differentiating criterion between prokaryotic and eukaryotic cells.: Eukaryotic cells have membrane-bound organelles; however, prokaryotic cells do not.
(T/F) Electron microscopy can be used for teh study of living speciments: False, preparation requirements kill the specimen.
(T/F) Bacteria virsues are examples of prokaryotic cells: False, bacteria are prokaryotic while viruses are non-living acellular structures.
Describe bacterial DNA: Bacterial DNA consists of a single circular chromosome.
What is a plasmid: A plasmid is a smaller extrachromosomal ring of DNA sometimes found in bacteria. It replicates independently of the bacterial chromosome.
(T/F) Bacertia contain ribosomes: True, but prokaryotic ribosomes are smaller than eukaryotic ribosomes.
Name the components of a typical bacterial cell.: Cell wall, cell membrane, cytoplasm, ribosomes, flagella, and DNA.
Where does respiration occur in the bacterial cell?: The cell membrane is the site of respiration in bacteria.
(T/F) All multicellular organisms are composed of eukaryotic cells.: True.
Which type of eukaryotic cells have a cell wall?: Plant cells and fungal cells have a cell wall.
(T/F) Plant cells have all of the organelles of an animal cell, plus a cell wall and chloroplasts.: False, plant cells do not have centrioles.
What is cytosol?: Cytosol is the fluid component of the cytoplasm.
What are the primary components of the cytoskeleton?: The primary components of the cytoskeleton are microtubules, microfilaments, and intermediate fibers.
Define the fluid mosaic model?: The fluid mosaic model states that a cell membrane consists of a phospholipid bilayer with proteins embedded throughout.
Is the interior of a cell membrane hydrophilic or hydrophobic.: The interior of a cell membrane is hydrophobic.
What is the function of the a transport protein?: A transport protein helps move polar molecules and cetain ions across the cell membrane.
What is a membrane receptor?: A membrane receptor is a protein (or glycoportein) that binds to
Can small polar and non-polar molecules easily cross the cell membrane?: Yes, because of their size, small polar and non-polar molecules can easily traverse the cell membrane.
How does a large charged molecule cross teh cell membrane?: A large charged particle usually cross the cell membrane with the help of a carrier protein.
(T/F) The nucleus is surrounded by a single-layered membrane.: False, the nuclear membrane is double layered.
How is material exchanged btw the nucleus and the cytoplasm?: The nuclear membrane contains nuclear pores that selectively allow for the exchange of materials.
What is a histone?: A histone is a structural protein complexed with eukaryotic DNA to form a chromosome.
What is the function of the nucleolus?: The nucleolus synthesizes ribosomal RNA (rRNA)
What is the function of a ribosome?: A ribosome is the sight of protein translation (assembly) during protein synthesis.
What is the gneral function of endoplasmic reticulum?: ER is involved in the transport of materials throughout the cell.
What is the function of smooth endoplasmic reticulum?: Smooth ER is the site of lipid synthesis and poison detoxification, and it is involved in protein transport within the cell.
The segment of DNA that acts as the template for transcription: anti-sense strand
non-template strand of DNA: sense strand;
it is identical in sequence to the mRNA being transcribed (w/ exception of uracil in place of thymine)
RMA polymerase moves along the _____ DNA strand in the _____ direction and synthesized the mRNA in the _____ direction: anti-sense;
3' to 5' direction;
5' to 3' direction
Transforming proteins are _____.: mutants
start codon: AUG
What is always the first codon to be translated?: Methionine;
therefore, always the first amino acid in the peptide chain prior to peptide modification and processing following translation.
- During this process, the terminal Met is typically cleaved.
What direction does the ribosome read the mRNA transcript?: 5' to 3' direction until the start codon - AUG is read.

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