/sci/ - Science & Math

shameless self bump. I'm not begging for answers, just some form of directed thinking. Give me a subject slightly more defined than just "Transport Vesicles" and I'll do my best to tell you all I know. Please /sci/, I'd really appreciate the interest.

How much energy does a mitochondria create? Would it be enough to power a small nanomachine?

I know it doesn't have much to do with your work, but its a serious question.

I have a good grasp of most biology concepts
Golgi apparatus:
functions
how it works
explain it
GO

which is the most important organelle? justify your answer, limit yourself to 3 sentences please.

oh and know the diff types of pumps for each of those, given that mitochondria vs chloroplasts vs certain vesicles have different kinds of proton exchangers, oriented in diff...orientations

n' shit

>>4222459
The golgi apparatus is the site of modification of the cells exports in a sense, although not all products which pass through it leave the cell. Proteins transcribed from DNA are modified and packaged in this organelle. Modifications are made by enzymes in the cisternae of the apparatus.

Sorry bob, I just really dont know much about nanomiachines to answer your question.

>>4222481

Its cool....here is another question for ya.

Cell Junctions, how do they work and what do they do?

Dude! I just finished this class. Taking Advanced Cell Biology right now.

Lemme just take out my flash cards...

What are the types of cell junctions? Compare the functions of each different type.

>biology

you can't be serious

>>4222489
>>4222489
>>4222489
Cell junctions come in 4 forms, Tight junctions Adherens junctions Gap junctions and Desmosomes.

They provide, in general anchorage and act as blockades for extracellular molecules, kind of forcing them intothe cells by giving them no choice. Tight junctions specifically also maintain orientation of cell surface proteins, so that they remain in the region for which their function is relevant.

Also I'm not going to write full on essay answers.

cell has a mutated genome, golgi aparantus no longer functions properly what happens to the cell. GOGOGOG CRITICAL THINKING HARD MODE

Everything you know about peroxisomes! Go!

>>4222510
>>4222510
Depends completely on the mutation. If its in the "junk DNA" no biggie, unless it shifts the reading frame of necessary genes. If it is a prevelant mutation from early stage development then the organism will fail. In terms of induced mutation at a later stage, it is STILL dependant on the mutation. A specific type of mutation really would need to be stated otherwise its too broad for me. thanks though.

>>4222501
>>4222501

Biology involves a fair amount of physics and chemistry at higher level education. I Maths Physics Biology and Chemistry A levels, they were fairly equal, Chemistry being the toughest, Maths the easiest. There are no soft Science subjects at a ceratainlevel

i'll tell you the right answers once you try it out

Sample questions
1. Evidence that mitochondria and chloroplasts arose by endosymbiosis includes
a) symbiotic relationship with the nucleus
b) characteristic structure of their ribosomes
c) their own genome
d) all of the above
e) b and c

2. The F0F1 ATP synthase is a multisubunit enzyme complex that projects from the ___ into the ___, generating ATP using the ___
a) outer mitochondrial membrane, cytoplasm, proton gradient across the OMM
b) outer mitochondrial membrane, intermembrane space,
c) inner chloroplast membrane, stroma,
d) inner mitochondrial membrane, cytoplasm, proton gradient across the IMM
e) inner mitochondrial membrane, matrix,

3. Nitric oxide is a paracrine signal molecule because NO:
a) has an extremely long half life.
b) is slow to diffuse.
c) is produced in very small quantities.
d) is unstable, with a short half life.
e) binds to cell surface receptors that are very plentiful.

4. In an active state of a G protein:
a) the a subunit binds to a target protein and the bg subunit remains bound to the receptor.
b) the a and bg subunits both can bind to target proteins.
c) the ab and g subunits both can bind to target proteins.
d) the g subunit can bind to a target protein and the ab subunit remains bound to the receptor.
e) all 3 subunits independently interact with target proteins.

5. Peptide hormones and growth factors act on target cells by binding to _______ receptors.
a) cell surface
b) cytosolic
c) nuclear
d) ER and golgi
e) All of the above

6. Activation of Ras DOES NOT require:
a) a GEF
b) a SH2 domain containing protein
c) an autophosphoylation event on a tyrosine residue
d) a GAP
e) a ligand

>>4222507
>>4222507
unfortunately not alot, even though they are a possible subject on the exam! They are involved in the catabolism of a fatty acids with aliphatic tails longer than 22 carbons, or Very long Chain Fatty Acids (VLCFAs). Thus they operate as a preceding digestive organelle for the mitochondria, by reducing the VLCFAs to smaller length chains which the mitochondria can use. Sorry to dissapoint with my crappy knowledge lol. Also unless I refresh the captcha i keep getting the same one every single fucking time. And it doesn't work.

>>4222517
>If it is a prevelant mutation from early stage development then the organism will fail

someone don't know shit 'bout suppressors

>>4222526
continued

1. Both prokaryotic and eukaryotic cells
a. carry out translation of proteins on ribosomes using DNA templates
b. carry out transcription of proteins on ribosomes using RNA templates
c. are separated from their external environment by a carbohydrate bilayer membrane
d. use DNA as genetic material and RNA as a carrier of information
e. use protein as genetic material and RNA as a carrier of information
2. The eukaryotic small ribosomal subunit initially binds at what structure on the mRNA?
a. A Shine-Dalgarno sequence
b. The poly A tail
c. The 7-methylguanosine cap
d. A TATA sequence
e. An AUG initiation codon
3. Which of the following properties of water make it the ideal solvent for cellular activities?
a. Water has a low heat of vaporization.
b. Water is a polar molecule that can form hydrogen bonds with itself and with other polar
molecules.
c. Water dissolves nonpolar molecules.
d. Water expands when it freezes.
e. none of the above
4. The genomes of salamanders contain ten times more DNA than the genomes of humans.
What would most likely account for this?
a. Salamanders genomes have ten times as many protein coding genes as humans.
b. Genomes increased in size during earlier evolution of all invertebrates and nonmammalian
vertebrates, but then reduced in size during mammalian evolution.
c. Salamander chromosomes contain unique types of histones that require unique DNA
sequences found only in salamanders.
d. Salamander genomes have a greater amount of non-coding and repetitive DNA sequences.
5. Why is yeast (Saccharomyces cerevisiae) an ideal model for cell biology?
a. it has a genome with a similar number of genes as the human genome
b. it can be readily grown in the laboratory, and has a rapid cell division time
c. many of the fundamental mechanisms that regulate cell growth, division, and function
in yeast are the same as in multicellular eukaryotic organisms
d. all of the above
e. b and c only

>>4222534
continued
6. Short segments of newly synthesized DNA on the lagging strand are called
a. Okazaki fragments.
b. replicons.
c. origins of replication.
d. lagging fragments.
7. A primary culture of mammalian liver cells is capable of only 50-80 normal cell divisions
before they suddenly die due to instability and degradation of the chromosomes. What is the
most likely reason for this observation?
a. a lack of histone deacetylase (HDAC) activity in the cultured cells
b. the origins of replication are no longer active in the cultured cells
c. a lack of telomerase activity in the cultured cells
d. the cultured cells exhaust their supply of DNA polymerase after multiple cell divisions
e. the cells could no longer play well together
8. Of the following statements concerning microtubules, which one is FALSE?
a. The location at which new microtubule formation originates in any one cell is based
solely on where in that cell the microtubules are required.
b. Dynamic instability of microtubules is determined in part by the rate of GTP hydrolysis.
c. Polarity of microtubules is important for determining the direction of movement of
dynein-based transport mechanisms.
d. Microtubules play an important role in movement of vesicles within a cell.
9. Which of the following mutations in a gene encoding a protein that is normally destined for
secretion from a cell would likely cause that protein to instead remain in the cytoplasm?
a. mutation of the gene such that the final 30 amino acids (at the C-terminal of the
protein) are missing from the protein
b. mutation of the gene such that polyadenylation of the mRNA does not occur
c. mutation of the gene such that the first 30 amino acids (at the N-terminal of the protein)
are missing from the protein
d. mutation of the gene such that the SRP encoding portion of the mRNA is not expressed

Pretty sceptical about you studying biology at a University, if that's all you can say about peroxisomes.
Maybe something about the reactions going there? The specific properties of the membrane of the peroxisome?

>>4222536
10. Of the following statements concerning mRNA splicing in eukaryotic cells, which one is
TRUE?
a. Splicing is a two step process that requires different snRNAs to assist in carrying out
the splicing reactions.
b. Pre-mRNAs go through an intermediate stage in the splicing process when the poly(A)
tail interacts with the 7-methylguanosine cap.
c. The splicesome removes exons and ligates introns together to form the final mRNA.
d. snRNPs are complexes consisting exclusively of protein, and make up the splicesome.
e. mRNA splicing occurs predominantly in the nucleus, except for the those mRNAs
encoding proteins required in the cytoplasm.
11. The signal recognition particle (SRP)
a. recognizes the signal sequence of newly transcribed mRNAs and targets them to the
ribosome.
b. recognizes the signal sequence on the amino terminal of proteins and targets them to the
ribosome.
c. recognizes the signal sequence on the amino terminal of proteins and targets them to the
RER.
d. recognizes the signal sequence on the amino terminal of proteins and targets them for
cleavage by the signal peptidase.
e. recognize the signal sequence of tRNAs and targets them to the signal processing
centre of the ribosome.
12. The structures and/or organelles associated with the secretory pathway are the:
a. plasma membrane, vesicles, mitochondria, lysosomes, RER.
b. Golgi apparatus, mitochondria, lysosomes, endosomes, plasma membrane.
c. RER, Golgi, lysosomes, vesicles, plasma membrane.
d. intermediate filaments, lysosomes, Golgi apparatus, plasma membrane, SER.
13. The important functional domain(s) of the matrix adhesion protein fibronectin is (are) a:
a. collagen-binding domain.
b. cell binding domain.
c. proteoglycan binding domain.
d. all of the above
e. a and c only

good luck

>>4222534
>>4222526
Quite alot of this seems to be closer to biochemistry/molecular genetics, but I'll answer the ones relevant to me. Hang on for a few minutes I will answer them, and thanks for the interest/effort.

>>4222539
>>4222539
Well specifically I'm studying Genetics. Cell Biology is a useful module, but its one I find fairly dull at times. Pretty sure I missed most of the lectures on peroxisomes. Sorry to dissapoint.

>>4222517

the mutantion causes the golgi apparatus to function at 30% of it normal functionality what happens to the cell, HARD MODE

>>4222550
Not much, as the golgi apparatus mostly exports proteins etc out of the cell.

Name all the subunits used in the electron transport chain within mitochondria. For each subunit name where it's genetic material is stored, what is it's input (NADH, FADH, etc) and what is it's output (# ions, succinate, etc)

How do adaptations to cold affect mitochondria membranes? What does this mean for the electron transport chain?

What are the TIM/TOM complexes?

How is a peroxisome created?

>>4222573

unless you get shit building up in the cell that needs to get out

>>4222573
FAILED, indeed it moves proteins around but proteins are very vital to the cell, REDEMPTION MODE; WHAT happens to the cell when proteins are less avaiable IE YOUR " not much" only slows protein movement

>>4222550
>the golgi apparatus to function at 30% of it normal functionality

What does this statement even mean? The golgi isn't like an electrical component that you can just dial up or down, it's effectiveness can't be encoded in a single number called its "functionality".

>>4222591

if there is a 70% reduction of average physiologic trafficking out of the TGN, then that would be pretty much "30% functionality"

>>4222580
damn winter break has turned my mind into muck(bichem major) thanks for the wake up call

Tell us how the electron transport chain works to generate ATP.

Bonus: Explain the Q cycle.

This kind of stuff might no be on your exam, but anyone who really wants to understand cell biology should know it.

>>4222942
Also, consider the following:

Uncouplers are poisonous compounds which carry protons from the innermembrane space of the mitochondria to the matrix, thus allowing the proton gradient generated by the electron transport chain to be dissipated without passing through ATP synthase.

Explain why this causes:
>an increase in body temperature
>increased sweating

Prolonged use can cause death. Why? (hint: think of what kind of physiological changes are brought about by extreme increases in body temperature).

>>4222946
Shit. Replace "increased sweating" with "weight loss."

> My face when biochemistry is just for failures who couldn't keep up with the mathematics required for a real chemistry degree so they opt for a field full of nothing but rote memorization instead

>>4222954
2/10

That's the best I can do.

>>4222954
That's why it starts with bio-

>>4222954
lol we take the exact same maths minus calc 3
>chem degrees are for people who can't handle the math required for a chemE degree