Chapter 1 - Cell Biology Flashcards
Cell membrane can be described as?
A lipid bilayer that contains protein channels, enzymes and receptors
Cholesterol does what for the membrane?
Increases membrane fluidity
The inside of the cell is + or - to outside and based on what?
Negative, Na/K ATPase (3Na+ out/2K+ in)
The Na+ gradient across a cell membrane is used for what?
Cotransport of clugose proteins and other molecules
Extracellular fluid plasma cations: Sodium, Potassium, Calcium, Magnesium?
Na+ 140, K+ 4, Ca2+ 5, Mg+2. 40% of TBW. Na is main driver.
Intracellular cations: Sodium, Potassium, Calcium, Magnesium?
Na+ 12, K+ 150, Ca2+ 10(-7), Mg+7. 60% TBW. K is main driver.
Extracellular plasma anions: Chloride, bicarb, SO4 2-, HPO4 3-, Protein, Organic Ions?
Cl- 103, HCO3 24, SO4 1, HPO4 2, Protein 16, Organic anions 5
What are desmosomes/Hemidesmosomes?
Adhesion molecules (cell-cell and cell-extracellular matrix), which anchor cells. IgG (type 2) to desmogleins causes pemphigous vulgaris - mucocutaneous blistering, tx w/ steroids. Can be tx like burn.
What are tight junctions?
cell-cell occluding junctions and form an impermeable barrier (ie epithelium)
What are Gap junctions?
They allow communucation between cells (connexin subunits)
What are G-Proteins?
Intramembrane proteins, transduce signal from receptor to response enzyme. Ex. Activates cAMP for ADH, TSH, PTH, calcitonin, glucagon.
What are ligand triggered protein kinases?
receptor and response enzyme are a single transmembrane protein
ABO blood type antigens are what type of antigen?
Glycolipids on cell membrane
HLA-type antigens are what type of antigen?
Glycoproteins on cell membrane
This cell cycle type is the most variable and determines cell cycle length?
G1 (first growth phase)
Growth factors affect the cell during what phase?
G1
What happens during prophase (first step in mitosis “M” phase)?
Centromere attachment, spindle formation, nucleus disappears
What happens during metaphase?
chromosomes align
What happens during anaphase?
chromosomes pull apart
What happens during telophase?
A separate nucleus reforms around each set of chromosomes
What happens during cytokinesis?
contractile ring forms and cells divide
What type of membrane does the nucleus have?
double membrane with the outer membrane contiguous with the RER
What is the nucleolus?
Area inside the nucleus, no membrane, where ribosomes are made
What happens in transcription?
DNA strand is used as a template by RNA polymerase for synthesis of an mRNA strand
What are transcription factors?
They bind to DNA and help the transcription of genes
How do steroid hormones work?
They bind to receptors in the cytoplasm, then enter nucleus, and acts as transcription factor
Thyroid hormone works how?
binds receptor in the nucleus and then acts as a transcription factor
Other transcription factors include?
AP-1, NF-KB, STAT, NFAT
How do initiation factors work?
They bind RNA polymerase and initiate transcription
How does a DNA PCR work?
Uses oligonucleotidesto amplify specific DNA sequences. Rapid. Specific. Good for HIV cause can test earlier with smaller amount. Good for TB cause TB is slow growing to culture. Has to have primers to specific targeted sequences - can be hard for viruses, that change sequences.
Purines include?
Guanine, adenine
Pyrimidines include?
cytosine, thymidine, uracil
What is translation?
Occurs when mRNA is used as a template by ribisomes for the synthesis of proteins
In glycolysis, 1 glucose generates what?
2 ATP and 2 Pyruvate molecules
Where does the Krebs cycle occur?
On the inner matrix of the mitochonria memranes. NADH/FADH2 is created
What is Gluconeogenesis and when is it utilized?
Mechanism by which lactic acid and amino acids are converted to glucose. Used in times of starvation or stress. Anaerobic. Driven by glucagon - acts on liver to convert alanine (among others) to glucose.
Why can’t fat and lipids be used for gluconeogenesis?
Because acetyl CoA (breakdown product of fat metabolism) cannot be converted back to pyruvate.
What is the Cori cycle?
An elegant mechanism for the hepatic conversion of muscle lactate into new glucose. Pyruvate plays a key role in this process. Requires lactate dehydrogenase. Liver injury can make it difficult to clear lactate.
What happens in the RER and in what tissue is it increased?
Synthesizes proteins that exported. Increased in pancreatic acinar cells
What happens in the SER and in what tissue is it increased?
Lipid/steroid synthesis, detoxification of drugs. Increased in the liver and adrenal cortex.
What happens in the Golgi apparatus?
modifies proteins with carbohydrates; proteins are then transported to the cellular membrane, are secreted, or are targted to lysosomes
What are lysosomes?
they have digestive enzymes that degrade engulfed particles and worn out organelles
What are Phagosomes?
They engulf large particles and fuse with lysosomes
What are endosomes?
They engulf small particles and fuse with lysosomes
Protein kinase C is activated by what and does what?
Activated by calcium and Diacylglycerol (DAG). It phosphorylates other enzymes and proteins.
Protein kinase A is activated by what and does what?
activated by cAMP. It phosphorylates other enzymes and proteins
What is Myosin?
Thick filament of muscle. Uses ATP to slide along actin to cause muscle contraction
What is Actin?
Thin filaments, interact with myosin
What are intermediate filaments?
Keratin (hair/nails), desmin (muscle), vimentin (fibroblasts)
What do microtubules do?
form specialized cellular structures- cilia, neuronal axons, mitotic spindles. Involved in the transport of organelles (latticework)
What are centrioles?
specialized microtubule involved in cell division (spindle fibers that pull chromosomes apart)
