Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
98 Cards in this Set
- Front
- Back
|
What are the general components of a eukaryotic cell?
|
1.Plasma membrane
2.One or more nuclei 3.Cytoplasm 4.Organelles |
|
|
What are the three mechanisms by which cells move materials?
|
1.Active/Passive transport
2.Gated Transport 3.Vesicular Transport |
|
|
How do small, uncharged molecules move inside the cell
|
Simple diffusion across a concentration gradient
|
|
|
How do small, water soluble molecules move inside the cell
|
Active or facilitated transport
|
|
|
What molecules can move across the cell membrane in special channels (i.e. membranes surrounding the RER)
|
Proteins in the process of synthesis
|
|
|
Give an example of gated transport
|
Movement of molecules through nuclear pores into/out the nucleus
|
|
|
How does vesicular transport occur?
|
By uptake of vesicles by cells via endocytosis or phagocytosis
|
|
|
How does selective transport of vesicles occur?
|
By the budding of vesicles of one cell binding to another cell.
|
|
|
When does this occur?
|
Biosynthetic-secretory pathway and the endocytic pathway in cells
|
|
|
What are the three types of vesicles involved with vesicular transport?
|
1.Clathrin-coated
2.COP-II 3.COP-I |
|
|
What do clathrin coated vesicles tend to be involved with?
|
1.Movement into the cell to cytoplasm
2.Movement from the Golgi to the cell surface |
|
|
What do COP-II vesicles tend to be involved with?
|
1.Movement from the ER to and through the Golgi
|
|
|
What do COP-I vesicles tend to be involved with?
|
1. Retrieval of membranes and contents
|
|
|
What is the plasma membrane and what is its function?
|
A selective barrier that regulates the passage of materials into/out of the cell.
Also transmits signals |
|
|
Cell membranes are (homogenous/non-homogenous)in nature
|
non-homogenous
|
|
|
What is a lipid raft?
|
Molecules group as a microdomain (less fluid than the membrane)
|
|
|
Enzymatically active areas of the membrane contain high amount of ________?
|
proteins
|
|
|
The fluid mosaic model of the cell membrane proposes that:
|
1. Membrane consists of a phospholipid bi-layer (50% mass)
2. Membrane has 50% mass in proteins (integral, transmembrane, and peripheral proteins) 3. Oligosaccharide chains on the extracellular surface |
|
|
The glycolipids and glycoproteins on the surface of the cell form the ______ with a (+,-) charge
|
glycocalyx, negative
|
|
|
How does the membrane act to regulate the intercellular env.
|
By acting as a selective barrier via the actions of integral proteins
|
|
|
What are the functions of integral proteins
|
1.Transport
2.Cell receptors 3.Enzymes 4.Cell adhesion |
|
|
Where are tight junctions (zonula occludens) located and what is their function?
|
a.Located on the luminal border between adj. epithelial cells
b.Limits the movement of proteins & lipids to that cell only. c. Allows cells to have different compositions/functions |
|
|
How big is the nucleus?
|
6-10 um diameter
|
|
|
How many layers does the nuclear membrane have?
|
2
|
|
|
What are the functions of the nucleus?
|
1.Protection, replication, synthesis, and expression of the genome.
2. Synthesis of large and small ribosomal subunits. |
|
|
Where are the two unit membranes of the nucleus continuous with each other
|
At nuclear pores
|
|
|
What is the perinuclear cisterna?
|
The space between the 2 nuclear membranes.
|
|
|
What can the outer nuclear membrane be continuous with?
|
the RER
|
|
|
What are the function of nuclear pores
|
1.Act as gated channels
|
|
|
What is the fibrous lamina?
|
Layer of intermediate filaments just inside the inner nuclear membrane
|
|
|
What is the fibrous lamina composed of?
|
Lamins a,b,c
|
|
|
What happens when they are phosphorylated?
|
The nuclear envelope disassembles
|
|
|
What is chromatin
|
uncondensed genetic material (DNA, histones, non-histone protein)
|
|
|
What is a nucleosome?
|
DNA wrapped around packets of 4 specific proteins (histones)
|
|
|
Heterochromatin is/is not capable of being expressed.
Euchromatin is/is not capable of being expressed. |
Heterochromatin: Not capable
Euchromatin: Capable |
|
|
What is a chromosome
|
1. A darkly-stained, rod-like body of condensed chromatin.
|
|
|
What is the basic unit of a chromosome?
|
A nucleosome.
|
|
|
What is the nucleolus
|
A dense aggregate of protein and nucleic acid.
|
|
|
What happens at the nucleolus
|
1.Transcription of ribosomal DNA by RNA polymerase I
2. Synthesis of ribosomal subunits |
|
|
What are the 3 components of the nucleolus?
|
1. The nucleolar organizing DNA
2. Nucleolema pars fibrosa (densely packed RNP fibers) 3. Nucleolema pars granulosa(maturing ribosmes) |
|
|
What are the number and size of nucleoli usually related to?
|
1.# of ribosomes produced
2.Protein synthesis act. of cell |
|
|
Where are polyribosomal proteins synthesized?
|
In the cytosol (enter the nucleus and associate w/ribosomes in nucleolus)
|
|
|
How does protein/polypeptide synthesis begin?
|
When the small ribosomal subunit binds to the m/tRNA in the cytoplasm. Large subunit binds afterwards
|
|
|
What are polyribosomes
|
The appearance of multiple ribosomes translating the same mRNA
|
|
|
Accumulations of ribosomes are _____?
|
basophilic
|
|
|
On what type of ribosomes are proteins destined for use in the cytosol translated?
|
Free ribosomes
|
|
|
Secreted, lysosome-used, and integral proteins are translated where?
|
Bound to RER
|
|
|
What is the structure of the RER?
|
Series of membrane-limited flattening interconnected cisterna containing ribosomes on the cytoplasmic surface.
|
|
|
What is the function of the RER?
|
1. Synthesis of proteins for secretion, use by other organelles, and integral membrane proteins.
|
|
|
What 4 characteristics will cells specialized for protein secretion have?
|
1. Abundant RER
2. Prominent golgi 3. Euchromatic nuclei 4. Dense membrane-bounded secretory products. |
|
|
How are proteins modified in the RER?
|
1.Signal seq. cleaved by sig. peptidases
2.Glycosylation of glycoproteins 3.Post-translational modification 4.Folded 5.Assembled w/other proteins |
|
|
What are the functions of the Golgi?
|
1. Major site of carb synthesis
2. Sorting station for material in the cell |
|
|
How does the golgi modify proteins?
|
1. glycosylation of proteins nad lipids
2. phosphorylation or sulfonation of glycoproteins |
|
|
What is the structure of the golgi?
|
- stack of 3-10 flattened membrane-bound cisternae with dilated rims
|
|
|
Where is the golgi located
|
near (often apical) to the nucleus
|
|
|
What are the 3 regions of the golgi?
|
Cis-golgi network (forming face)
Medial golgi cisterna Trans golgi cisterna |
|
|
What are the major digestive organelles of the cell
|
Lysosomes
|
|
|
What are the enzymes that catalyze degradative functions called in lysosomes?
|
hydrolases
|
|
|
What is the structure of a lysosome?
|
Single-unit membrane with a number of morphologic appearances.
|
|
|
How is a low pH maintained in a lysosome?
|
By membrane-bound ATP-driven pump (Exchanges NA+ for H+)
|
|
|
How are materials digested by lysosomes?
|
endo/pinocytosis, receptor-mediated endocytosis, phagocytosis, or autophagy
|
|
|
What are proteasomes?
|
multi-hydolase compounds that digest single cytoplasmic proteins
|
|
|
Accumulations of SER are baso, eosinophilic?
|
eosinophilic due to protein content of membranes
|
|
|
What are the functions of the SER?
|
1.Synth. of steroid hormones
2.Detox of lipid-sol. drugs 3.Convert water-insol drugs to more water-sol. drugs 4.Synth. of lipids for lipoproteins for cell membrane 5.Synth. of phopholipids for cell membrane 6.Glycogen metabolism 7.Ca++ ion sequestration |
|
|
What are the functions of peroxisomes
|
1.Degrade toxic molecules, part. in the liver and kidney
2.Beta oxidation of long-chain FA's 3.Can be involved in purine metabolism |
|
|
How do oxidases work?
|
By removing hydrogen
|
|
|
What is the byproduct?
|
Hydrogen peroxide
|
|
|
What does catalase do?
|
converts hydrogen peroxide to water and oxygen
|
|
|
What is Zellweger syndrome?
|
Defects in the transport enzymes that move peroxisomal enzymes into the membrane.
|
|
|
Mitochondria are present in all cells except _____
|
RBC's
|
|
|
What is the s(x) of mitochondria?
|
Two unit membranes that form the intermembrane space and matrix compartment
|
|
|
What are the tubular cristae
|
The projections of the inner mitochondrial membrane.
|
|
|
Where is most of the mitochondrial protein made?
|
In the nucleus (nuclear DNA) and made on cytoplasmic ribosomes.
|
|
|
What are the functions of the mitochondria?
|
1.Conv. of pyruvate to Acetyl-CoA
2.ATP formation 3.Ca++ sequestering 4.lipid metabolism 5.processing of intermediates in steroid synthesis |
|
|
What are the 3 components of the cytoskeleton?
|
1.Microtubules
2.Microfilaments 3.Intermediate Filaments |
|
|
What are microtubules?
|
Unbranched tubular structures composed of the protein tubulin.
|
|
|
What do microtubules do?
|
1.Support the force-generating actions of cilia and flagella
2.Form the mitotic and meiotic apparatus/spindle |
|
|
What do the drugs colchicine, vinblastine, vincristine do and what are they used for?
|
Break down microtubules; used for cancer treatment
Taxol: microtubule stabilizing |
|
|
What are microfilaments composed of?
|
Actin
|
|
|
What are the functions of microfilaments?
|
1.Motility of cytoplasmic comp's
2.form a support network under the plama membrane |
|
|
What is the "molecular motor" that moves actin?
|
myosin
|
|
|
What are the functions of intermediate filaments?
|
1.Provide tensile strength
2.Insert into desmosomes and hemidesmosomes. |
|
|
What are the three types of cell junctions?
|
1.Occluding Junctions
2.Anchoring junctions 3.Communicating junctions |
|
|
What is the function of occluding junctions?
|
To regulate the flow of material from the lumen/surface of an epithelium to the lateral intercellular space between the epithelial cells
|
|
|
What do anchoring junctions do?
|
provide adhesion between cells
|
|
|
Where are zonula adherens located?
|
at the junctional complexes in epithelial cells
|
|
|
What is the zonula adherens molecule composed of?
|
E-cadherin: transmembrane adhesion molecule
|
|
|
What is the adhesion of zonula adherens dependent on?
|
Ca++ presence
|
|
|
What is the fascia adherens located?
|
cardiac muscle cells
|
|
|
What is another name for a macula adherens?
|
desmosome
|
|
|
On what side of the macula adherins is an attachment plaque through which intermediate fibers run?
|
cytoplasmic side
|
|
|
Between the cells of a macula adhesions, what are the extracellular parts of the transmembrane glycoproteins a part of?
|
Ca++ dependent cadherin cell adhesion molecules
|
|
|
What does a hemidesmosome do?
|
provide adhesion btw. a cell and the basement membrane. (think thick skin)
|
|
|
how are communicating junctions connected?
|
by transmembrane channels or small pores
|
|
|
what do connexons do
|
allow diffusion of small molecules btw. cells
|
|
|
how much electrical resistance is there btw. cells at gap junctions
|
little
|
|
|
What is the structure of connexons
|
6 integral membrane proteins in a circular arrangement
|
|
|
Where do gap junctions occur
|
1.Epithelials
2.Cardiac muscle 3.Bone cells 4.Smooth muscle 5.Nerve cells |
