1. 8-10 Flashcards

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1
Q

The cell, 2 compartments:

A

cytoplasm + nucleus

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2
Q

Plasma membrane (PM), composed of:

A

phospholipids, proteins, cholesterol, oligosaccharides

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3
Q

PM, functions:

A

recognition & regulation; a selective barrier that maintains the intracellular env distinct from the extracellular env

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4
Q

PM, properties:

A

Thickness 7.5-10nm; composed of 45% lipid, 50% protein, 5% carb

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5
Q

PM, activities:

A

endocytosis, exocytosis, pinocytosis (invaginations of PM pinch off as vesicles, eventually fuse w lysosomes), phagocytosis (“cell eating”)

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6
Q

Mitochondria

A

Matrix is protein rich and contains DNA, tRNA, rRNA, mRNA.

Cristae - folds of mito membrane that increase SA

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7
Q

Endoplasmic Reticulum (ER)

A

Intercommunicating channels that form a continuous membrane and enclose a cisterna.
2 types: rough ER, smooth ER

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8
Q

Rough ER

A

Dotted with ribosomes.
Prominent in cells specialized for protein secretion.
Saclike and parallel stacks of cisternae.
Segregates proteins not destined for cytosol

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9
Q

Ribosomes

A

Electron-dense particles composed of 4 types of RNA and >80 proteins.
Stain blue with haemotoxylin

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10
Q

Ribosomes, cont

A

PROTEIN TRANSLATION.
In euks, RNA is synthesized in nuc. mRNA encode for AA’s, and ribosomes decode this and translate into protein.
Individual ribosomes are held together by mRNA to form polyribosomes.
Have 2 diff subunits - 60S and 40S

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11
Q

Smooth ER

A

Continuous with RER, lacks polyribosomes.

Specialized functions - synthesis of steroid hormones & phospholipids.

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12
Q

Smooth ER, muscle cells:

A

Aids in contraction (called sarcoplasmic reticulum). Sequesters & releases Ca2+ during contraction

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13
Q

Golgi Apparatus

A

Post-translational modification of proteins (adds carbs to tail of proteins).
Processes proteins, gets them into vesicles to transport outside cell.
Rough ER sends proteins to Golgi.

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14
Q

Golgi, cont

A

Has a trans face and cis face.
Cisternae near rough ER are convex, form cis face.
Opposite, concave face is trans.

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15
Q

Endosomes

A

System of vesicles & tubules in the cytosol near cell surface (early endosomes) and deeper (late endosomes)

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16
Q

Endosomes, cont

A

Contain ATP-driven proton pumps to acidify interior compartment; acidification causes separation of ligand/receptor complexes.
Receptors recycle back to PM, ligands are contained within late endosome

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17
Q

Lysosomes

A

Intracellular digestion and turnover.
Internally acidic, contain hydrolytic enzymes.
Abundant in phagocytic cells (i.e. macrophages)

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18
Q

Lysosomes, cont

A

0.05-0.5um
Packaged in trans-Golgi network.
Delivered in clathrin-coated vesicles to late endosomes forming endolysosomes, which mature into lysosomes

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19
Q

Primary lysosomes

A

not involved in digestion

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20
Q

Secondary lysosomes

A

fused with phagosome, heterogenous in size/appearance

21
Q

Residual body

A

Indigestible material remaining within vacuoles (i.e. tattoo ink)

22
Q

Heterophagosomes

A

Fusion of lysosome with phagosomes containing foreign materials

23
Q

Lipofuscin

A

The yellow pigment that accumulates with age from auto and hetero-phagic vacuoles

24
Q

Autophagosomes

A

fusion of lysosome with intracellular organelles

25
Q

Proteasomes

A

Multiple protease complexes; digest ubiquinated proteins. Removes excess/improperly folded proteins

26
Q

Peroxisomes

A

Spherical. Oxidize organic substances (transfer H to O –> hydrogen peroxide). H2O2 is removed by catalase.
Oxidize long chain and branched chain FAs

27
Q

Secretory vesicles or granules

A

Found in cells that store a product. Membrane bound.

28
Q

Zymogen granules

A

Vesicles with digestive enzymes

29
Q

Centriole

A

Cylindrical bodies of short microtubules. 9 bundles of 3 microtubules.

30
Q

Centrosome

A

2 perpendicular centrioles, each surrounded by granular material (brown haze). Duplicates before cell division, moves to opposite poles of cells in order to organize mitotic spindle

31
Q

Microtubule

A

Heterodimers of a and b tubulin. Can polymerize and form microtubules. Form basis for centrioles, basal bodies, cilia (respiratory cells), flagella (sperm)

32
Q

Molecular inclusions

A

Usually accumulated metabolites.
Lipids - triglyceride
Carbs - glycogen deposits
Pigments - colored substances (melanin, lipofuscin)

33
Q

Cell nucleus, main components:

A

Nuclear envelope
Chromatin
Nucleolus
Nuclear matrix

34
Q

Nuclear envelope

A

2 unit membranes separated by a narrow space - perinuclear cistera.
Impermeable to ions and proteins.
External membrane is continuous with ER; ribosomes attached to outer surface.

35
Q

Fibrous lamina

A

closely associated with internal membrane of nuc envelope. 3 main proteins: Lamins A, B, C.
In non-dividing cells - chromosomes are associated with the FL

36
Q

Nuclear pore

A

Where inner and outer membranes of nuc envelope fuse and leave a gap.
Pathways between nuc and cytoplasm.
Ions and small mlcs can pass freely; larger mlcs require active ATP transport

37
Q

Chromatin I

A

In non-dividing cells: chromosomes in diff degrees of uncoiling.
2 types: heterochromatin, euchromatin

38
Q

Heterochromatin

A

e- dense, appears as coarse clumps assoc w nuclear lamina. Unexpressed DNA

39
Q

Euchromatin

A

Less coiled chromosomes appear as finely dispersed granular material.
Site of active transcription
Cells synthesizing proteins have more eu than hetero

40
Q

Chromatin II

A

In dividing cells - chromosomes become supercoiled. Chr II is coiled strands of DNA bound to histones

41
Q

Histones

A

protein complex that allows for chromatin coiling (chr. II)

42
Q

Diploid F cells

A

One X chromosome remains euchromatic. The other is condensed and inactive, forms Barr body

43
Q

Nucleolus

A

Assembles ribosomal subunits.
Rich in rRNA and protein.
All protein components synthesized in the cytoplasm.
Nuclear organizer DNA: base sequences coding for rRNA

44
Q

Nucleolus, pars fibrosa

A

densely packed ribonucleoprotein fibers closely associated with nuclear organizer DNA. Primary transcripts of rRNA genes.

45
Q

Nucleolus, pars granulosa

A

Granules representing maturing ribosomes

46
Q

Microvilli

A

Fingerlike projections on apical surface of cells, especially absorptive cells where it has thick glycocalyx (i.e. in intestines).
Microvilli + glycocalyx (cell coat) = brush border
Has actin core; actin filaments extend from microvillus into body of cell, forming terminal web

47
Q

Cilia & Flagella

A

Motile processes covered by cell membrane.
Microtubular core, 2 central surrounded by 9 pairs = axoneme
Nexins (protein bridges) link adjacent pairs of microtubules. Each pair has A and B microtubule. Dyenin (ATPase) arms extend from A

48
Q

Stereocilia

A

Long, non-motile microvilli.

Found in epididymis and on hair cells in inner ear

49
Q

Microplicae

A

Fold-like extensions of cytoplasm present on luminal epithelial cells (cornea, esophagus). Increase SA and surface adherence of fluids