Chapter 1 Flashcards
What is the cell size of the mycoplasma?
0.2 micrometer
What is the cell size of a yeast cell?
6 micrometer
What is the cell size of a fibroblast?
20 micrometer
What is the cell size of a nerve cell?
20 micrometer - 10 centimeter
What is the cell size of a plant cell?
50 micrometer
What are all cells bounded by?
Lipid Bilayer
What does the cell membrane do?
a. segregates the interior of the cell from the external environment
b. has a system that controls import into and export out of the cell
What does it mean to be amphipathic?
It has both a hydrophilic and hydrophobic end
What is an example of amphipathic?
The phospholipid with hydrophilic head and hydrophobic tail
What does the genome do?
Codes for all cellular structures
What does information transfer do?
Express information stored in genetic code
What does energy utilization do?
Harness energy to build more complex components
What is the big leap of ‘scientific faith’?
To believe that all the molecules necessary for cellular function arose spontaneously (amino acids, nucleotides, sugars, lipids)
What is the larger leap of ‘scientific faith’?
To believe that cells can specialize
How many compartments does a prokaryotic cell have?
One compartment - several regions but one membrane-bound compartments
What are the two domains of prokaryotes?
Bacteria and archaea
Both domains are what organisms?
Unicellular organisms
Are cell walls found in all prokaryotes?
No
What is an example cell that does not have a cell wall?
Mycoplasma
Is mycoplasma affected by antibiotics that attack cell walls?
No
What is a gram-positive bacteria?
It has a cell wall surrounding the plasma membrane and strain reacts directly with components of the wall
What is the gram-negative bacteria?
It has a second membrane surrounding the cell wall and strain is prevented from reacting
What region does the gram-negative bacteria have?
Periplasmic space
What is a periplasmic space?
Region between the outer and inner membrane that has its own characteristic set of proteins and other components
In what conditions does one typically find arachaea?
Under extreme environmental conditions
At a molecular level, many components of archaea are most similar to?
Eukaryotes, NOT bacteria
What are the three classifications of prokaryotes classified by their temperature affinity?
Mesophiles, psychrophiles, thermophiles
What conditions do psychrophiles live in?
Grow best between 15 - 20C but some ca live at 0C
Cold water and soil
What conditions do mesophiles live in?
Grow best between 25 - 40*C
What conditions do thermophils live in?
Grow best between 50 - 60C but some can tolerate up to 110C
What are the three classifications of prokaryotes classified by their pH affinity?
Acidophiles, Alkalinophiles (basophiles)
What conditions do acidophiles grow in?
Grow best at pH beow 5.4
What conditions do alkalinophiles (basophiles) grow in?
Maintain internal pH around 7
Protected by their cell walls against external extremes
Some grow in pH 12
What are the three classifications of prokaryotes classified by their oxygen requirements?
Aerobic, anaerobic, facultatively anaerobic/aerobic
What conditions do aerobic prokaryotes live in?
Requires oxygen
What conditions do anaerobic prokaryotes live in?
Does not require oxygen
What conditions do facultatively anaerobic prokaryotes live in?
Can switch between aerobic and anaerobic
What are the two major compartments of a eukaryotic cell?
Nucleus and cytoplasm
What does the nucleus do?
Holds the genetic material (some don’t have nucleus)
What is the cytoplasm?
Everything between nucleus and plasma membrane
What regulates nuclear pores?
Nuclear pore complexes
NPC
Nuclear pore complexes
What does NPC control?
Entry and exit of nucleic acids and proteins
What does NPC do not control?
Entry and exit of gases, water, and ions
In nucleus, high concentration of DNA is equivalent to?
Gel of high viscosity (thick gel due to high weight of DNA)
What is the consequence of high concentration of DNA?
Localization becomes important
Does organelles synthesize proteins?
No, except mitochondria and chloroplasts. Proteins must be imported
What is the secretory pathway?
Proteins made in RER -> vesicle -> golgi -> vesicle -> plasma membrane
What are the properties of a membrane?
It can pinch off and fuse moving content and membrane proteins from compartments
What does lumen of ER provide?
Provides an oxidizing environment that is important for fading proteins and assembling multisubunit oligomers
What does transport proteins do?
a. Maintain various ionic milieus within compartments
b. Maintain various pH milieus within compartments
In which organelles is the concentration Ca2+ high (10^-3 M)?
a. mitochondria: intermembrane space b. nucleus: lumen of nuclear envelope and endoplasmic reticulum
In which organelles is the concentration Ca2+ low (10^-8 M)?
Cytosol
Order the organelles with low pH to high pH
Lysosome, late endosome, trans-golgi network, early endosome, mitochondria intermemebrane space, cytosol/nucleus/ER, mitochondrial matrix
The outer membrane of the envelope is contiguous with?
Rough endoplasmic reticulum membrane
Lumen in-between is contiguous with?
ER lumen
What is an example of a non-membrane-bound subcomparments?
Nucleolus, inclusion bodies, cajal bodies
Do all eukaryotes have one nucleus?
No
Cell with no nucleus
Mammalian RBCs
What is syncytium?
Hundreds of nuclei in a common cytoplasm
Plasma membrane allows?
a. Internal environment different from ECM
b. Communication between cells
What crosses the membrane the fastest?
Gases and other small hydrophobic molecules
What crosses the membrane medium fast?
water, but requires aquaporins
Aquaporins react to?
Osmotic pressure
What crosses the membrane very slowly or have no movement?
ions (without a channel or carrier)
Gating is controlled by?
a. ligand binding
b. voltage
c. temperature change
If with the gradient, what is required?
ion channel proteins
If against the gradient, what is required?
carrier proteins
Why did the cell which became the nucleus relinquish?
Genes transferred into nucleus from organelle after endosymbiotic event
Why did the cells which became mitochondria and chloroplast keep?
Because of apparatus of modern prokaryotes
Why did mitochondrial genomes have genes for their ribosomal rRNA molecules but not for ANY of their ribosomal proteins?
Most of genes for ribosomal proteins were transferred to nuclear genome during evolution because it would be better synthesized in the cytoplasm
Why did the original cell los its nucleoid region?
One prokaryotic cell engulfed another, and the engulfed cell took over the genetic functions for the combined unit
What does viruses use for their hereditary material?
Some use DNA, some use RNA
What is epigenetic inheritance?
Information passed on that is not carried in the DNA sequence
Examples of epigenetic inheritance
a. Proteins influencing others’ folding
b. Centriole partner creation - always perpendicular to the existing ones
Instead of replication, more genes are in the human genome devoted to?
repair DNA damage
Mistakes that occur during replication is caught by?
a. 3’ to 5’ exonuclease activity
b. mismatch repair pathway
Mistakes that occur via environmental effects is fixed by?
repair pathways
What happens if some mistakes do not get fixed?
become mutations
Anatomy of mitochondria
two phospholipid bilayers, matrix, intermembrane space, contains DNA
What happens in mitochondria?
a. glycolysis
b. Kreb’s cycle
convering envegy from glucose to ATP and NADH
Anatomy of chloroplasts
two phospholipid bilayers, stroma, intermembrane space, thylakoid membranes and spaces inside; contains DNA
What does plastids perform?
Biosynthetic reactions like nitrogenous base and amino acid synthesis
What does plastids develop from?
Undifferentiated proplastids
What are amyloplasts?
differentiated to synthesize and store starch
What are chromoplasts?
Differentiated to contain various pigments; synthesize carotenoids
To which organelles are the proteins delivered posttranslationally?
Nucleus, peroxisome, mitochondrion
Signal difference of posttranslation and cotranslation
sorting signal
signal sequence
To which organelles are the proteins delivered cotranslationally?
ER
How does the proteins arrive at nucleus and peroxisomes?
Through a channel in a folded configuration
How does the proteins arrive at mitochondria and chloroplast?
Through a channel, kept unfolded before transport and refolded post-transport
How does the proteins arrive at the ER, Golgi, endosomes, and plasma membrane?
Nascent protein being synthesized on a ribosome has its translation halted until it goes to RER, there translation resumes while translocation ensues as the protein emerges from the ribosome. From the RER, proteins get to Golgi via budding and fusing vesicles
Why is the proteins moved via coated vesicles?
It is essential for budding process, help deform membrane to bud, fall off after budding
Pinocytosis
a. cells that secrete a lot, must bring back a lot
b. recycling plasma membrane
c. maintaining different phospholipid percentages
Receptor mediated endocytosis
phagocytosis
The forward transport from ER to Golgi to plasma membrane
Anterograde; exocytic
The reverse transport from plasma membrane to Golgi to ER
Retrograde; endocytic
What are proteins that are found in most compartments in cells?
Chaperone proteins
Do chaperone proteins need enzymatic activity?
No
What do chaperone proteins do?
a. help proteins get folded properly
b. help proteins get unfolded in preparation for translocation across a membrane
When do chaperon proteins help proteins get folded properly?
a. when they are first made
b. after they just entered a compartment
c. after heat or other stress to a cell
What does the crenated RBCS under the microscope look like? Why?
Spikey balls; due to dehydration or exposure to hypertonic conditions
When does most of the cytoskeletal fibers rearrange?
At the beginning of mitosis, meiosis, and then again during telophase again
What are the three different cytoskeletal fibers?
Microtubules, intermediate filaments, and actin filaments
Microtubules
a. Made of alpha-tubulin and beta-tubulin dimers
b. stabilized by interaction with other proteins
c. rearranges
d. subunit dynein
Intermediate filaments
Do not have subunits
Actin filaments
a. made of actin dimers
subunit myosin
Where does the positional information occur?
barr bodies next to nuclear envelope, rRNA genes in the nucleolus, Golgi bodies adjacent to RER, centrioles templating perpendicularly on existing centrioles, dorsal-ventral gradients of proteins inside cell cytoplasm
Positional information involves?
Cytoskeleton
There is basal and apical region in this cell
Polarized cell
Enzymes are highly specific
Organized in pathways, meaning that it allows to achieve a concerted goal in steps
To maintain homeostasis, enzymes have
Feedback mechanisms
Signal transduction
transducing a signal from outside the cell to an effector region inside the cell
Bacteria and archaea divide by
Binary fission
Yeast and some other fungi divide by
Budding
Eukaryotes divide by
Mitosis and meiosis
Fertilized zygote is
totipotent
Somatic cells are diploid
Not always, depends on an organism
Embryonic stem cells asre
pluripotent
What type of stem cell is multipotent?
immune cells
All stem cells have what ability?
self-renew
Terminally differentiated cells have lost what?
the capacity to divide
Totipotent
can give rise to all cells of the organism and extraembryonic tissue layer
Pluripotent
Most organism cells; broad activities in regeneration
Multipotent
Differentiate into few
