Eukaryotic cell 1 & 2 Flashcards
1
Q
cell consists of 2 main components
A
nucleus and cytoplasm
2
Q
largest structure
A
nucleus
3
Q
nucleus contains
A
- DNA organized in chromosomes
- nucleoproteins
- newly synthesized RNA
4
Q
nucleoproteins involved in
A
DNA and RNA synthesis and folding of DNA
5
Q
2 forms of DNA in nucleus
A
heterochromatin and euchromatin
6
Q
heterochromatin
A
dark, clumped peripherally, silenced (not involved in RNA synthesis)
7
Q
euchromatin
A
light, scattered, actives (involved in RNA synthesis)
8
Q
nucleus is bound by
A
nuclear envelope
9
Q
nuclear envelope
A
- 2 concentric membranes, - continuous with the ER,
- contains pores to allow movement of substances between nucleus and cytoplasm
- consist of nucleoporins
- become leaky w age
10
Q
nucleolus
A
- roughly spherical in nucleus
- involved in ribosomal RNA synthesis and ribosome assembly
11
Q
nucleolus consists of
A
- nucleonema; dense, darkly staining, partially assembled ribosomes
- pars amorpha; DNA coding for rRNA
12
Q
main organelles in cytoplasm
A
- ER
- golgi apparatus
- ribosomes
- mitochondria
- lysosomes
- centrioles
13
Q
ER latin
A
rete means net
14
Q
ER
A
network of membranes, connected to nuclear envelope
15
Q
2 types of ER
what are each involved in
A
smooth and rough
rough are studded w ribosomes; involved in protein synthesis and modification and packaging of proteins before transport to golgi
smooth; no ribosomes and involved in synthesis and storage of phospholipids, cholesterol, glycerides, glycogen and steroids, also involved in drug detoxification and calcium storage (muscle)
16
Q
ribosomes are responsible for
A
protein assembly: structural, chemical messengers, enzymes
17
Q
increased protein production requires more
A
ribosomes
18
Q
ribosomes consist of
A
rRNA and protein
19
Q
ribosomes pathway
A
synthesized in nucleus
assembled in nucleolus
transferred to cytoplasm
20
Q
ribosomes can be
A
free (single unit) or poly-ribosomes
*** listen to lec for this part
21
Q
golgi apparatus consist of
A
series of membranous sacks called cisternae
22
Q
golgi apparatus communicates
A
w ER and cell surface via vesicles
23
Q
major functions of golgi apparatus include (3)
A
- modification and packaging of secretory products (hormones and enzymes)
- synthesis of glycoproteins and glycolipids for cell membrane
- packages enzymes for use within the cell
24
Q
mitochondria shape
A
sherical to rod-shaped
25
mitochondria have their own
DNA so can self replicate
26
mitochondria supply
cell's energy, numbers proportional to cell's metabolic activity
27
mitochondria membrane
- double; outer and inner
- inner folded into cristae to increase SA, site of energy production, ATP formed within matrix (oxidative phosphorylation)
28
mitochondria evolved from
bacteria that were engulfed by another single-celled organism
allowed a switch from inefficient process of oxidative phosphorylation
29
all mitochondrial DNA inherited from your
mother
30
mitochondria also key regulators of
apoptosis (cell death)
31
lysosomes produced by
golfi apparatus
round membrane-bound vesicles
32
lysosomes contain around
50 types of acid hydrolases (digestive enzymes)
33
lysosomes functions 93)
- degrade defunct organelles
- digest carbs, lipids, proteins, nucleic acids
- kill intracellular microorganisms
34
primary lysosomes
inactive enzymes
(primary becomes secondary becomes residual body)
35
secondary lysosome
- fused w damaged organelle (autophagy)
- phagocytosed material (phagocytosis)
- activated enzymes
36
residual body lysosome
- exhausted lysosome
- filled w undigested debris
- extruded from cell or remains as lipofuscin granules (increase w age)
37
centrioles, how many
usually 2, near nucleus, in centrosome
aligned at right angles to each other
38
centrioles are
cylindrical structures composed of microtubules (9 microtubule triplets)
organizing centres for microtubules; cell division and cytoskeleton of the cell
39
cytoskeleton is
framework of several types of proteinaceous filament and tubules within the cell
40
cytoskeleton consist of
- microfilaments (5nm diameter, actin)
- microtubules (25 nm, tubulin)
- intermediate filaments (10-12 nm mainly keratins)
41
biological membranes are permeable to
lipid soluble molecules, but not to lipid insoluble
42
principle functions of biological membranes
protection
absorption and transport
adherence
compartmentalization
providing internal SA
cell to cell communication
43
structure of biological membranes
- semi-fluid phospholipid bilayer
- hydrophilic heads on the surfaces
- hydrophobic tails in between
44
integral proteins
embedded in the bilayer
some span entire width of membrane: transmembrane proteins
45
peripheral proteins
bound to membrane surface
46
plasma membrane PROTEIN functions
anchoring
cell recognition
enzymes
carriers
channels
47
carrier vs channel
- carrier; move substances across membrane
- channel; movement of water and ions across the membrane (like a pore)
48
cholesterol molecules are embedded within the _____ region of the bilayer
hydrophobic
49
on the extracellular surface of the membrane there are
glycoproteins and glycolipids
the carb chains extend into extracellular environment and form the glycocalyx
50
glycocalyx functions
- cell recognition
- adhesion
- adsorption of molecules
- mechanical and chemical protection
51
specializations of plasma membrane: tight junctions aka occluding junctions
- located beneath apical surface of cell
- partial fusion of lipids of adjacent cells' membranes
block the passage of solutes into intercellular spaces
- each tight junction forms a band around apical portion of cell; zonula occludens
52
desmosomes
- adhering or anchoring junctions
- membrane proteins or proteoglycans bind the adjacent cell
- linked to cytoskeleton
- strong
53
zonula adherens (belt desmosome)
continous band just below the tight junctions
54
macula adherens (spot desmosome)
spots arranged circumferentially
55
hemidesmosomes
between basal protion of cell and basement membrane in epithelial cells
56
zonula occludens + zonula adherens + macula adherens=
junctional complex
57
gap junctions (communication junctions)
2 cells locked together by membrane proteins (connexins)
form channels for movement of molecules such as ions, nutrients and signalling chemicals (large organelles such as mitochondria cannot pass)
58
luminal surface specializations: microvilli
short finger like projections of plasma membrane
increase SA fro absorption
brush border
epithelial cells
59
luminal surface specializations; sterocilia
- NOT CILIA
- long microvilli; branch and anastomose
- increase SA for absorptions
60
luminal surface specializations; cilia
- long
- wavelike, synchronous motility --> propels fluid, mucus
- 9 microtubule doublets are a central pair (9+2)
- at their base is a basal body, v similar to a centriole
61
passive diffusion
- lipids, lipid soluble molecules (alcohol, steroids)
- hydrophilic molecules and ions pass at transmembrane protein channels
- down a concentration gradients
- no energy expended
62
facilitated diffusion
- larger hydrophilic molecules; too big for membrane channels, bind to carrier proteins
- rate of transport is determined by number of carrier proteins
- down a concentration gradient
- no energy expended
63
active transport
- transport molecule across membrane irrespective of concentration gradient
- ATP required
64
endoxytosis
- inward bulk transport
- extracellular material is packaged into a vesicle at the cell's surface
- cell membrane bulges inwards forming pseudopodia and pinches off to form vesicle
- vesicles fuse with lysosomes
65
endocytosis; pinocytosis
extracellular fluid
66
endocytosis; phagocytosis
extracellular solid material including bacteria
67
receptor-mediated endocytosis
receptors within a clathrin -coated pit on cell surface bind specific molecules
form a clathrin-coated vesicle
68
exocytosis
- outward bulk transport
- expelled material may be waste or secretory products (proteins, steroid, lipids)
69
exocytosis; proteins released form cell one of 2 ways:
- constitutive secretion; continuoulsy in coated vesicles
- regulated secretion; stored in vesicles until signalled for release
70
exocytosis; steroid and lipids leave the cell by
passive diffusion or are stored until bulk release
71
apoptosis
- genetically programmed cell death
- common in embryonic tissue
- response to genetic errors
- absent in tumour cells
72
2 pathways of apoptosis
- intrinsic; stress, UV radiation, DNA damage, activates signalling cascade within mitochondria
- extrinsic; initiated via death ligands, soluble, bound to cytotoxic T cells
73
necrosis
- cells exposed to conditions that they cannot tolerate and die
- uncontrolled cell death
- lysis of cells
- inflammatory response
74
which of the following statements about eukaryotic cells is incorrect
the nucleolus contain heterochromatin and euchromatin, both responsible for ribosomal RNA synthesis
The Golgi apparatus is involved in the synthesis of the glycoproteins and glycolipids that form the cell membrane
Nuclear morphology is distinct for different cell types and can be used to identify cells that are abnormal, including those that are neoplastic
The smooth endoplasmic reticulum synthesises phospholipids and steroid hormones, and in muscle cells is an important store of calcium ions
the nucleolus contain heterochromatin and euchromatin, both responsible for ribosomal RNA synthesis
75
Which of the following statements about eukaryotic cells is INCORRECT?
Transmembrane integral proteins can function as channels and carrier proteins to move ions and compounds across the plasma membrane
Characteristics of the glycocalyx on the surface of red blood cells determines blood type (i.e., A, B, O, and AB)
Gap junctions consist of connexin proteins that form channels between cells for the movement of ions, nutrients, and signalling molecules
Desmosomes are located immediately below the apical surface of the cell, where they form a tight band to block the passage of solutes into the intercellular space
Desmosomes are located immediately below the apical surface of the cell, where they form a tight band to block the passage of solutes into the intercellular space
76
Which of the following statements about eukaryotic cells is INCORRECT?
Mitochondria produce ATP within their matrix and the number within a cell reflects the cell’s metabolic activity; they are also key regulators of apoptosis
Characteristics of the glycocalyx on the surface of red blood cells determines blood type (i.e., A, B, O, and AB)
Gap junctions consist of connexin proteins that form channels between cells for the movement of ions, nutrients, and large molecules (i.e., glucose)
Lysosomes are vesicles that contain acid hydrolases that digest phagocytosed material and degrade defunct organelles
Gap junctions consist of connexin proteins that form channels between cells for the movement of ions, nutrients, and large molecules (i.e., glucose)
