Fiser.01.CellBiology Flashcards by Suniah Ayub

Name three types of proteins contained in the lipid bilayer

Channels, enzymes, receptors

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What component of the cell membrane increases fluidity?

Cholesterol

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How many sodium and potassium ions are pumped by the Na/K-ATPase and in which direction?

3 Na+ out, 2 K+ in

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What is the relative charge intracellularly vs extracellularly

Cells are negative intracellularly relative to extracellularly

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What is the Na+ gradient used for in terms of the cell membrane?

Used for co-transport of glucose, proteins

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What is the function of desmosomes / hemidesmosomes?

Adhesion molecules, anchor cells

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What type of adhesion do desmosomes do?

Cell-cell adhesions

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What type of adhesion do hemidesmosomes do?

Cell-ECM adhesions

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What do “tight junctions” do?

Cell-cell occluding junctions to form an impermeable barrier

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Give an example of a tissue that uses tight junctions

Epidermis

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What is the function of “gap junctions”?

Allow communication between cells

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What is the subunit that creates “gap junctions”?

Connexin subunits

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What is the function of G-proteins?

Transmembrane proteins that allow signal transduction from receptor to response enzyme

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How are G-proteins different from ligand-triggered protein kinases?

Receptor and response enzyme are a single TM protein

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What happens when a ligand binds to a ligand-activated ion channel?

Results in conformational change that opens or activates the channel

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What happens when a ligand binds to a ligand-activated protein kinase?

Activates the kinase domain which phosphorylates substrate protiens

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What happens when a ligand binds to a G-protein

Activates an enzyme that generates second messengers

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Name two examples of intracellular second messengers

cAMP, inositol 1,4,5 triphosphate

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What molecule determines ABO blood type antigens?

Glycolipids on the cell membrane

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What molecule determines HLA-type antigens?

Glycoproteins (Gp) on the cell membrane

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Describe the process of osmotic equilibrium in terms of two areas of unequal solute concentration across a semipermeable membrane

Water moves from area of low sulte concentration to an area of high solute concentration to approach osmotic equilibrium

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What is the [x] of sodium in extracellular vs intracellular fluid in mEq/L?

140 mEq extracellular / 12 mEq intracellular

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What is the [x] of potassium in extracellular vs intracellular fluid in mEq/L?

4 mEq extracellular / 150 mEq intracellular

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What is the [x] of calcium in extracellular vs intracellular fluid in mEq/L?

5 mEq extracellular / 10^-7 mEq intracellular

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What is the [x] of magnesium in extracellular vs intracellular fluid in mEq/L?

2 mEq extracellular / 7 mEq intracellular

What is the [x] of chloride in extracellular vs intracellular fluid in mEq/L?

103 mEq extracellular / 3 mEq intracellular

What is the [x] of bicarb in extracellular vs intracellular fluid in mEq/L?

24 mEq extracellular / 10 mEq intracellular

What is the [x] of sulfate (SO4^2-) in extracellular vs intracellular fluid in mEq/L?

1 mEq extracellular / 0 mEq intracellular

What is the [x] of phophate (HPO4^3-) in extracellular vs intracellular fluid in mEq/L?

2 mEq extracellular / 116 mEq intracellular

What is the [x] of protein in extracellular vs intracellular fluid in mEq/L?

16 mEq extracellular / 40 mEq intracellular

What is the [x] of organic anions in extracellular vs intracellular fluid in mEq/L?

5 mEq extracellular / 0 mEq intracellular

Name the four steps of the cell cycle

G1, S, G2, M

What occurs in the S phase (2)

Protein synthesis, chromosomal duplication

What occurs in the M phase (2)

Mitosis, nucleus division

Which phase is the most variable?

Which phase determines cell cycle length?

Which phase is affected by growth factors?

Name the four phases of mitosis

Prophase, Metaphase, Anaphase, Telophase

What occurs during prophase (3)?

Centromere attachment, spindle formation, nucleus disappears

What occurs during metaphase (1)?

Chromosome alignment

What occurs during anaphase (1)?

Chromosomes pulled apart

What occurs during telophase (1)?

Separate nucleus refomrs around each set of chromosomes

How many membranes does the nucleus have?

Two, double membrane

What intracellular structure is the outer nuclear membrane continuous with?

Rough ER

Where is the nucleolus located?

Inside the nucleus

Does the nucleolus have a membrane?

Nope

What function does the nucleolus serve?

Ribosome synthesis

Describe the template, enzyme, and product for DNA transcription

Template: DNA strand, enzyme: RNA-polymerase, product: mRNA

What is the function of transcription factors?

Bind to DNA and help the transcription of genes

Where do steroid hormones bind to their receptor?

In the cytoplasm

Where do the steroid hormone-receptor complex go?

Into the nucleus to act as a transcription factor

Where does the thyroid hormone bind to its receptor?

In the nucleus

What does the thyroid hormone-R complex do after that

Acts as a transcription factor

Name four other transcription factors

AP-1, NF-kappa-B, STAT, NFAT

What are initiation factors?

Bind to RNA polymerase to initiate transcription

Name the three functions of RNA-polymerase while transcribing

Unwinds the DNA helix; Catalyzes formation of a transient RNA-DNA helix; Releases RNA as a single strand copy while DNA rewinds

How does the RNA-polymerase know what to transcribe?

Moves between a DNA start sequence and stop sequence

What is the DNA polymerase chain reaction?

Uses oligonucleotides to amplify specific DNA sequences

Name the two purine bases

Adenine, guanine

Name the three pyramidine bases and the different nuclear strands they are used in

Cytosine, thymine (only in DNA), uracil (only in RNA)

What is the base-pairing with guanine and how many hydrogen bonds does it form?

Guanine-cytosine form 3 hydrogen bonds

What is the base paring with adenine and how many hydrogen bonds does it form?

Adenine-thymine/uracil forms 2 hydrogen bonds

What is translation (in terms of protein synthesis)

mRNA is used as a template by ribosomes for the synthesis of proteins; As the ribosome moves along the mRNA, new amino-acyl tRNA complexes bind to the A-site of the ribosome, after which the new peptide bond is formed with the nascent polypeptide chain; Ribosome moves along and ejects the tRNA to make room for a new one

What are ribosomes?

Have small and large subunits that read mRNA, bind appropriate tRNAs with amino acids, and eventually make proteins

Name the input and output of glycolysis

One glucose molecule generates 2 ATP and 2 pyruvate molecules

\*\*PHOTO\*\* How many membranes do mitochondria have?

On which mitochondrial membrane does the Krebs cycle take place?

Inner membrane

What is the input and output of the Krebs cycle

2 pyruvate molecules (from one glucose) creates NADH and FADH2

What are the inputs into the electron transport chain?

NADH and FADH2 enter the ETC to create ATP

How many ATPs do you get overall from one glucose molecule?

36 ATP from one glucose

What is gluconeogenesis and what two substrates can be used?

Mechanism by which lactic acids and amino acids are converted to glucose

What is the Cori cycle and name a critical molecule for this cycle

Occurs in the liver converting muscle lactate into glucose (GN), pyruvate is critical

Why are fats and lipids not used for gluconeogenesis?

Acetyl CoA is the breakdown product of fat metabolism and cannot be converted back to pyruvate

What does the rough ER do?

Synthesizes proteins that are exported

Name a cell that has high levels of rough ER

Pancreatic acinar cells

What does the smooth ER do? (2)

Lipid/steroid synthesis; detoxifies drugs

Name two cells with lots of smooth ER

Hepatocytes, adrenal cortex

What does the Golgi apparatus do and name its three targets

Modifies proteins with carbohydrates and targets for cell membrane, secretion, or lysosomes

What do lysosomes do?

Have digestive enzymes that degrade engulfed particles and worn-out organelles

What are phagosomes?

Engulfed large particles that fuse with lysosomes

What are endosomes?

Engulfed small particles that fuse with lysosomes

What activates protein kinase C? (2)

Calcium and diacylglylcerol (DAG)

What activates protein kinase A? (1)

Cyclic AMP (cAMP)

What are myosin?

Thick filaments in muscle

What are actin?

Thin filaments in muscle

How do myosin and actin interact?

Myosin uses ATP to slide along actin to cause muscle contraction

Name three examples of intermediate filaments

Keratin (hair/nails); desmin (muscle); vimentin (fibroblasts)

Name two functions of microtubules

Form specialized cellular structures (mitotic spindles, cilia, neuronal axons); Involved in transport of organelles by forming an intracellular latticework

What is a centriole and what does it do?

A specialized microtubule involved in cell division, forms spindle fibers which pull chromosomes apart