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Year 1 Histology > Cell Structure > Flashcards

Cell Structure Flashcards

1
Q

features of absorbative cell

A

microvilli

many cell junctions

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2
Q

What is a Cytoskeleton?

A

A dynamic (changes rapidly) system of protein filaments in the cytoplasm of a eukaryote that gives the cell shape and the capacity for movement of substances

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3
Q

What is diapedesis?

A

The crawling of cells along a surface

allows the passage of white blood cells through capillary walls into the tissues.

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4
Q

What are the functions of the cytoskeleton?

A

Responsible for:

Large-scale cellular movements such as diapedesis and cytokinesis and muscle cell contraction

Changes in cell shape and fluidity that accompany embryonic development

Also provides machinery for intracellular movements e.g movement of organelles/vesicles and anaphase

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5
Q

What are the 3 intracellular movements that involve the Cytoskeleton?

A

Transport of organelles from one place to another

Segregation of chromosomes into 2 daughter cells during anaphase of mitosis

cytokinesis

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6
Q

What are the three types of protein filaments within the cytoskeleton?

A

Microtubules

Intermediate Filaments

Actin Filaments

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7
Q

What are the characteristics of Microtubules?

A

They are…

long stiff, cylindrical intracellular structures

20nm diameter

composed of tubulin protein

grow out of the centrosome and create a system of tracks for transport vesicles, organelles and other cells components

Utilize motor proteins for movement

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8
Q

What are motor proteins?

A

proteins that bind to organelles within a cell and move them along microtubules (and sometimes actin filaments)

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9
Q

What are the characteristics of Intermediate Filaments?

A

Intermediate in size

10nm in diameter

Stable rope-like polymers

Made of fibrous proteins which give mechanical strength

STRONGEST OF THE 3 CYTOSKELETON PROTEINS!

Also found in the nucleus under the nuclear envelope (forming the nuclear lamina)

attach organelles to each other or organelles to the cell membrane

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10
Q

Which type of protein filament is rope-like and forms a nuclear lamina under the nuclear envelope of a cell - therefore strengthening the envelope?

A

Intermediate filaments

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11
Q

True or False

Protein filaments participate in cell junctions

A

True

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12
Q

What are the characteristics of Actin Filaments (microfilaments) ?

A

Small

made of filamentous protein

formed from a chain of globular actin molecules

Found in cross-linked bundles and networks (stronger)

Forming contractile skeleton in cell

used in muscle contraction

involved in regulating cell shape

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13
Q

What are integrins?

A

Cell surface receptors that attach cells to the extracellular matrix and mediate mechanical and chemical signals

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14
Q

Which protein filament type forms the cell cortex?

A

Actin Filaments in a network of cross-linked bundles

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15
Q

What are Cell Inclusions?

A

various nutrients or pigments that can be found within the cell, but do not have activity like other organelles. Examples of cell inclusions are glycogen, lipids, and pigments such as melanin

can be cell products or ingested material

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16
Q

What are the 4 types of cell inclusions?

A

Glycogen

Lipids

Pigment Granules

Secretory Granules

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17
Q

What is glycogen?

A

a large branched polysaccharide found in the cytoplasm of several cell types including liver and muscle

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18
Q

What are lipids?

A

non-membrane bound droplets in the cytoplasm that vary in size

Require special stain to see with LM

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19
Q

What are the 2 types of lipid cell inclusions?

A

Neutral

Metabolic

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20
Q

Give an example of Neutral Lipid Cell Inclusions and where they are found in the body

A

Triglycerides

stored in adipose tissue

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21
Q

Give an example of metabolic lipid cell inclusions and where they are found in the body

A

Steroids as a substrate for estrogen or cortisol

22
Q

What are pigment granules?

A

Melanin (to block UV damage)

heme (oxygen transport)

23
Q

What are secretory granules?

A

membrane bound vesicles that contain inactive enzymes, proteins and neurotransmitters

24
Q

What is the nuclear envelope?

A

The envelope surrounding the nucleus which consists of 2 lipid bilayer membranes and is perforated by nuclear pores

the membranes are continuous with the ER (although structurally different)

25
Q

What is the nuclear lamina?

A

a network of protein filaments that support the nuclear envelope

26
Q

What do the nuclear pores on the nuclear envelope do?

A
  • Actively transport selected molecules to and from the cytoplasm
  • Critical role in regulating gene expression
  • ringed by many proteins
27
Q

What is the Nucleolus?

A

non-membrane bound

the region of the nucleus where different chromosomes carrying genes for ribosomal RNA cluster (1 per nucleus) are found

site of production of rRNA

Contains both granular and fibrous material

role in cell cycle regulation / sensor for DNA damage

28
Q

features of secretory cells

A
29
Q

cell membrane structure / function

A

phospholipid bilayer that is formed spontaneously

hydrophobic tails face inwards and are shielded by hydrophilic groups which face outwards on either side

fluid allowing lateral diffusion of membrane proteins and cell mobility

highly permeable to water oxygen and small hydrophobic molecules e.g ethanol

impermeable to large and/or charged ions

cell-cell and cell-ECM adhesions (interactions)

30
Q

components of cell membrane

A

50% phospholipids

cholesterol reduces fluidity and improves stability

31
Q

define pinocytosis

A

when cells take up fluid and small molecules to form small vesicles by budding

32
Q

define potocytosis

A

type of receptor-mediated endocytosis

33
Q

define endocytosis

A

general process

when cells ingest large molecules to form endosomes (membrane bound vesicle)

34
Q

define phagocytosis

A

type of endocytosis

when cells ingest large solid particles to form a phagosome

35
Q

exocytosis

A

opposite of endocytosis

fusion of vesivles with membrane to discharge its contents

buds if cell membrane may also pinch off to form extracellular vesicles that acts as transport vesicles

36
Q

mitochondria functions and structure

A

site of energy production via oxidative phosphorylation and ATP production

metabolism of amino acids and lipids

biosynthesis of haem and Fe-S clusters

act as a sensor for health of cell and trigger apoptosis

Outer (double) membrane smooth

Inner (double) membrane folded to form cristae

Two compartments: Outer compartment & Inner matrix

37
Q

difference between cilia/flagellae and microvilli

A
  • Cilia (and flagellae): extensions of the microtubule cytoskeleton that actively move
  • Microvili : extensions of the actin microfilament cytoskeleton, no active movement. they act to increase surface area
38
Q

structure of cilia

A

microtubule core

Each cilium contains nine pairs of microtubules forming the outside of a ring, and two central microtubules

known as 9 + 2 arrangement

microtubules joined by nexin

Between the nine outer pairs are motor proteins called dynein which allow the movement

coated in plasma membrane

39
Q

structure of centrioles

A

Centrioles are cylindrical structures, found in animal cells

groupings of microtubules arranged in a 9 (triplets) + 0 pattern

help to organize the assembly of microtubules during cell division

40
Q

difference between cell cortex and cytoskeleton

A

cell cortex provides support to the plasma membrane whereas the cytoskeleton maintains the overall shape of the cell

41
Q

tight junctions

A

•act as barriers, preventing the passage of substances between adjacent cells

  • Help maintain position of membrane proteins (called polarity)
  • found near top of cells
42
Q

adherens junctions

A

attach cells to each other and to the cytoskeleton

e.g •zonula adherens (actin extension)

and desmosomes (intermediate fillaments extension)

43
Q

Hemidesmosomes

A

•type of anchoring junction

  • they attach epithelia to the basement membrane and hence to the tissues beneath e.g. skin

•Made of integrins, laminin, collagen (all ECM proteins)

44
Q

gap junctions

A

allow direct communication between adjacent cells

permits coordinated cell activity e.g cardiac cycle

consist of connexins which together form connexons

45
Q

junctional complexes

how are the different junction types arranged within a cell?

A

tight junction , adherens junctions/gap junction , anchoring junctions

top of cell bottom of cell

46
Q

RER and SER

A

ER = series of flatenned membranous channels and vesicles

RER is covered by ribosomes that produce proteins for export

involved in synthesis, folding, modification, and transport of proteins.

SER involved in lipid synthesis and export of large molecules

47
Q

golgi apparatus

A

series of flattened membrane sacs

processes and packages and sorts proteins received from ER into membrane bound vesicles

48
Q

lysosome

A

vesicle containing digestive enzymes which are kept separated by membrane.

Destroys material from outside & within cell

Produced from ER and Golgi Apparatus

Acid pH inside

49
Q

peroxisome and proteosome

A

special type of lysosomes containing catalase, converts hydrogen peroxide (toxic) to water (harmless)

proteosome - degrades ubiquitinated (degraded) proteins

50
Q

Differences between eukaryotic and prokaryotic cells

A

Prokaryotic cells Eukaryotic cells

(bacteria, mycoplasmas, (other algae, fungi, protozoa,

blue-green algae) multicellular plants and animals)

  1. Size 0.1-5.0 µm - allows ions and organic molecules that enter them to quickly spread to other parts of the cell
  2. Size ranging from 10–100 µm – requires more complex organelles and cytoskeleton
  3. No nuclear envelope
  4. Prominent nuclear envelope
  5. No nucleoli
  6. Nucleoli present
  7. No histones
  8. DNA complexed with histones
  9. Few intracellular membranes
  10. Many membrane-bound organelles
  11. 60-70s ribosomes
  12. 70-80s ribosomes
51
Q
A

Year 1 Histology (10 decks)

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