Week 11 Recall Questions Flashcards
What characterizes the bacterial chromosome and ribosomes and differentiates them from eukaryotic
ones?
(Not finished)
Bacterial chromosomes have a single circular DNA, while eukaryotes have linear DNA (have terminal ends to them, are arranged usually in multiple linear chromosomes).
Bacterial ribosomes function in polypeptide assembly or chains of amino acids that are being put together. (Primary, secondary, tertiary, quaternary sequence as proteins), while eukaryotic ribosomes do this as well, they also make products that function in organelles of endomembrane system
What is the function of plasmids?
How are plasmids used in biotechnology?
Function is to convey resistance to antibodies, provide flexibility to changes in their environment. Such as, giving them the ability to use new nutrients.
Function like a first aid box.
-smaller, about 5% the length of bacterial chromosome
In biotech they can be used to insert genes of interest from 1 cell into another cell plasmids.
- done when we clone a gene, copy it, or to get the product the gene produces (ex: insulin)
Could eukaryotes have plasmids?
(Not finished?)
Yes, some occur naturally in eukaryotes
What are the differences between eukaryotic and prokaryotic cells?
(Not finished)
Prokaryotic cells:
- lack membrane bound nucleus
- lack a lot of internal membrane bound specialized structures called organelles
- Nucleoid region: site of genomic DNA (chromosomes)
- 50S + 30S = 70S (sevburg sedimentation rate)
- have capsule
Eukaryotic cells:
- have membrane bound nucleus
— has double membrane (or nuclear envelope with pores)
- have many organelles
— ER
— Golgi apparatus, etc
- linear DNA
- 60S + 40S = 80S
Where are bacterial ribosomes produced?
Where are eukaryotic ribosome produced?
Bacterial ribosomes are produced in the cytoplasm.
Eukaryotic ribosomes are produced in the nucleolus as SSU and LSU and moved to cytoplasm where they come together and are used for the translation of mRNA into polypeptides.
What is produced by free ribosomes?
What is produced by bound ribosomes?
Free ribosomes produce:
- proteins like cytosol
- products vary by location, local proteins are produced in fluid of cytoplasm.
Bound ribosomes produce: (bound to nuclear envelope)
- products that are inserted into membranes
- products that function inside organelles of endomembrane system
- products that are secreted from the cell (exocytosis)
What is the function of histones?
Function is to package DNA into structural units called nuleosomes.
Histones are the main proteins in chromatin. And chromatin’s are a combination of DNA and proteins which makes up the contents of a cell nucleus.
Because DNA wraps about histones, they also play a role in gene regulation.
Not packed into chromosomes = chromatin
Condensed into chromosomes using histones, b/c they’re positively charged proteins and therefore naturally attracted to DNA, which as an overall negative charge.
What is the function of a nuclear pore?
It is a large complex of proteins that allows small molecules and ions to freely pass or diffuse, into or out of the nucleus.
Products made in the nucleus, such as ribosomal subunits are able to move out.
What is the function of the endomembrane system and what are the main components?
Made up of
- nucleus (nuclear envelope)
- endoplasmic reticulum
- lysosomes
- various vesicles
- Golgi apparatus
- plasma membrane
This Internal membrane system helps the cell to produce products, such as proteins and then get them to their destination.
Function: it’s a group of membranes and cell organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins.
What are the differences of SER and RER and what is their respective function?
Both a part of endoplasmic reticulum (ER)
Smooth ER (SER):
- no ribosomes attached
- function in phospholipid production
- function in detoxification of drugs and poisons.
- cisternae
Rough ER (RER):
- covered with bound ribosomes
- function in protein synthesis
- structure is maze like, structure is called cisternae = flattened membranous sacs
What is the function of the Golgi complex?
Receives proteins from the ER (by vesicles) and further processes/modified them and then sorted for transport to their eventual destinations: lysosomes, the plasma membrane, or secretion
Structurally and functionally different than ER, not maze like, but separate individual pockets or cisternae folded membranes. (Not physically attached to these sacs)
Analogy: shipping and receiving centre.
Has CIS and Trans face
Vesicles are small membrane bound sacs
— function to transport cell products like proteins between parts of the endomembrane system. In cytoskeleton transport molecules using parts of cytoskeleton and motor proteins.
How do the cis- and trans-side of the Golgi-complex differ?
Proteins enter the Golgi on the side facing the ER (cis side)
Proteins exit on the opposite side of the stack, facing the plasma membrane of the cell (trans side)
Both are essentially responsible for the task of sorting proteins and lipids that are received at the cis face or released at the trans face by the organelle
What are the final destinations of some of the vesicles produced by the Golgi -complex?
- Lysosomes
- the plasma membrane
- or secretion
What is the function of lysosomes?
How do they maintain and acidic pH and how is this beneficial?
Lysosomes are membrane bound with hydrolytic enzymes (digestive enzymes)
In order to keep enzymes active, lysosomes use active transport to pump H+ inside the lysosome.
— have very high acidic pH, that’s required for digestive enzymes to be active.
The cytoplasm has a more basic pH, so the acidity projects the cell.
— so say some lysosomes rupture, it won’t digest the cell itself b/c the enzymes inside vesicles are neutralized by the basic pH of cytoplasm.
Also function with autophagy
What is authophagy and why is it beneficial?
Means self eating.
Refers to cells recycling worn-out or damaged cell organelles.
- fuses a lysosome to organelle to auto phagocytose it (eat it)
- digestion is a hydrolysis process
What are the functions of vacuoles?
What is a key function of vacuoles in plant cells?
Large membrane bound structures, sac-like
Serve functions in food storage, contractile functions in protists.
Many functions in plants such as, energy storage in seeds, store toxins, pigments, and water.
— plants rely on the water crew takes between their central vacuole and their cell wall to give them form (tonicity)
What is the Theory of Endosymbiosis?
What is the main statement?
(Not finished and needs to be revised)
Postulated events that’ve driven evolution of eukarya and their cell organelles, specifically mitochondria and chloroplasts.
Eukaryotic cell organelles evolved from free-living prokaryotes
- the mitochondria are thought to originate from an aerobic prokaryote that lived as an Endosymbiont within an anaerobic prokaryotic
- the chloroplasts are thought to originate from a photosynthetic prokaryotic that lived as an endosymbiont within a aerobic cell that already had mitochondria
What is the sequence of main events according to the Endosymbiotic Theory (Fig 21.17)
(Needs to be revised)
- Ancestral prokaryote (likely domain archaea) that was anaerobic respiring, engulfed an aerobic bacteria (also prokaryote)
- mutually beneficial: bacteria protected by larger cell. And bacteria provided to larger host cell aerobic metabolism = ability to deal with O2 and produce a lot more ATP
- (Only in some cell populations) photosynthetic bacteria (ancestors of cyanobacteria) were engulfed by host cell —> formation of chloroplasts
What are lines of evidence suggesting the mitochondria and chloroplasts have bacterial characteristics and are related to bacterial groups?
Be specific, give at least 4 pieces of evidence.
(Needs to be revised)
- Both replicated by binary fission. Replicate inside eukaryotic cells, fairly independent of the main cell (euk) that uses mitosis or chromosome sorting.
- Presence if double membrane. Both double or triple.
— Inner membrane has same structure and protein composition as living bacteria.
- host cell membrane and inner membrane (originally from prokaryote)
- enzymes and enzyme systems for metabolism are similar too and located in inner membrane - Presences of their own DNA.
- a single circular chromosome without histone proteins.
- able to sequence this and look at relationships, which show they most closely match with prokaryotic organisms. - Contain their own ribosomes. Similar to prokaryotes but not cytoplasmic eukaryote ribosomes.
- genes often referred to what we call 16S rRNA = ribosomes inside mitochondria and chloroplasts are most similar to prokaryotic ribosomes (bacteria)
- 16S rRNA are for ribosomal RNA genes that form small subunit (these most related to bacteria)
— ribosomes have own DNA = contain protein coding, non-coding genes, similar to prokaryotes. Have own transcription and translation machinery.
How did eukaryotes solve the increased need for energy due to their increased complexity?
They took advantage of aerobic prokaryotes that use O2 and therefore are able to produce more ATP through cellular respiration.
What is the main function of mitochondria?
Is the “powerhouse of the cell” a good description?
Function: they transfer energy in cells, the energy from nutrients and make ATP for the cell (cellular respiration)
How many membranes do mitochondria have?
What are the names of the different compartmental spaces (between/inside the membranes)?
Bean like structure with double membrane (origin in prokaryotic ancestors)
- has outer, inner membrane, intermembrane space, matrix
Intermembrane space where mitochondria pumps protons
What is the main function of chloroplasts?
Is the “powerhouse of the cell” a good description?
General function: site of light rxns for photosynthesis
Essentially a cell organelle that has a 3 membrane structure.
- outer, inner, thylakoid membrane
Thylakoid membrane where light rxns of photosynthesis take place, they sit in a gelatinous fluid of the chloroplast of the stroma (the fluid).
Inside thylakoids there’s a space called thylakoid lumen, this is where protons are pumped.
What are the general functions of the cytoskeleton?
- It spatially organizes the contents of the cell
— like aiding in the correct positioning of organelles - generates coordinated forces that enable the cell to move and change shape.
- supports plasma membrane
- gives cell overall shape
- provides tracks for the transport of vesicles
