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Medicine Sem 1 > Cytology week3,4,5 > Flashcards

Cytology week3,4,5 Flashcards

1
Q

What are lysosomes responsible for and what do they contain

A
  • Intacellular digestion
  • recycling cellular components
    They contain around 40 hydrolitic enzymes that break down macromolecules
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2
Q

Name the 4 hyrolitiic enzymes in lysosomes

A
  • Nucleases
  • Proteases
  • Phospholipases
  • Phosphates
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3
Q

Explain the formation of lysosomes

A
  • Lysosmal hydrolases is synthesied in the rER then transferred to the golgi apparatus where it is modified with M6P for lysosmal targetting
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4
Q

Explain the process in the digestion of external materials

A

-The membrane of the phagosome vesicle fuses with the lysosomes.
- This mixes the endocytosed materials with the lysosomal emzyme activating proton pumps in the lysosmal membrane, allowing digestion and forming a secondary lysosome(heterolysosomes)

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5
Q

What happens in Autophagy

A

-Lysosomes degrade excess or defective cells through autophagy.
-Autophagosomes form around unwanted cellular componentes and fuse with lysosomes for digestion.

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6
Q

What do indigestible materials form

A

They form residul bodies which can accumulate as lipofusion in long live cells(heart muscle and neurons)

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7
Q

Describe the structure and size of proteasomes and where they are found

A
  • Large non membrane bound protein complexes
  • Located in the cytoplasm and nucleus
  • They consist of a cylindrical structure with 4 stacked rings
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8
Q

What is the difference between proteasomes and lysosomes

A

Proteasomes target indiviudal proteins whereas lysosomes digest organelles or membranes by autophagy

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9
Q

What is the role of mitochondria?

A

It is responsible for aerobic respiration, ATP production, providing energy for cellular activities
- They oxidise pyruvate releasing more ATP than gylcolysis

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10
Q

Describe the structure of mitochondria

A
  • Elongated, highly dynamic
  • Has 2 membranes, an outer sieve like membrane, and a folded inner membrane called cristae, which increases the surface area and house key enzymes for energy production
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11
Q

Describe the inner membrane of the mitochondria

A
  • It contains specialised phospolipds
  • It is highly impermeable to ions, hosts transport proteins
    and the electron transport chain and ATP synthase for oxidative phosphorylation
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12
Q

What is the role of proteasomes

A

They degrade damaged or unecessary proteins

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13
Q

How is ATP produced in the mitochondria

A

-Electrons from the ETC create a proton gradient across the inner membrane and then protons flow back through ATP synthase, generating ATP.

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14
Q

What is mitochondrias role in Apoptosis?

A

During cell stress, mitochondria release cytochrome C, triggering apoptosis by activating cellular proteases

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15
Q

What is the function of peroxisomes?

A
  • They produce and degrade hydrogen peroxide through oxidase and peroxidase
  • They detoxify harmful substances, especially in the liver and kidney.
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16
Q

What is the role of peroxisomes in metabolism

A

It breaks down long fatty acid chains and synthesising bile acids and cholesterol

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17
Q

How are peroxsisomes formed

A
  • By budding from the ER or by growth and divison of existing peroxisomes.
  • Their proteins are synthesised in the cytosol and imported using targeting sequences
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18
Q

What does cytoskeleton consist of?

A
  • Microtubules
  • Micro filaments(Actin filaments)
  • Intermediate filaments
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19
Q

What is the function of Cytoskeleton

A
  • It provides structural supprt
  • Determines the cell shape
  • Enables movement of organelles and vesicles
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20
Q

Explain the structure of Microtubules

A
  • Hollow rigid tubular structures
  • Made of alpha and beta tubulin subunits
  • Linked side by side in structures like cilia
  • Highly dynamic
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21
Q

What is the microtubules function in intracelluler transports

A
  • It facilitates vesicle,organelles and complex transport
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22
Q

What is the microtubules function in cell organization?

A
  • They extend the ER and assist vesicle movement through Golgi apparatus
  • They maintain cell shape and polarity
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23
Q

What is the cell cycle

A

Cycles of growth and division

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24
Q

NAME the phases of the cell cycle

A
  • G1 Phase
    -S phase
    -G2 phase
  • Mitosis
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25
Q

Explain the 4 phases in the cell cycle

A

G1 PHASE
- Where active RNA and protein synthesis occurs, increasing cell volume
S PHASE
- DNA replication, histone synthesis and centrosome duplication happens
G2 PHASE
- Proteins required for mitosis accumulate
MITOSIS
- Cells divide, completing the cycle

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26
Q

What is the role of Cyclins and CDK(

A

-They regulate the cell cycle by activating phase specific proteins,
- Whe each phase is complete, the cyclin is removed and a new cyclin guides the cell into the next phase

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27
Q

What is the role of checkpoints and tummor supressor proteins

A
  • Specific checkpoints monitor conditions and DNA integrity pausing the cycle if issues arrises
  • Tumour supressor proteins such as p53 help stop the cycle for repair or tigger cell apoptosis if damages are irreperable.
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28
Q

Explain what happend in the G0 phase

A
  • Differentiated cells enter the G0 phase, where the cell cycle is apsued
  • Cells like liver cells can re-enter the cycle , while cells like the mucle and nerve cells stay in the G0 phase permanently.
  • External signals can re-activate G0 cells
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29
Q

Explain the structure of the microfilaments

A

-Made out of actin subunits and they are
- Thin
-Flexible
-Highly dynamic

and they have polarised filaments that enable cell motility and contraction

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30
Q

What is Mitosis?

A

It is the process of cell division where a parent cell divides to produce 2 daughter cells with identical sets of chromosomes.

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31
Q

What is the process of prophase

A
  • Chromosomes condense becoming visible chromosomes, each w 2 chromatids joined at the centromere .
  • The Nucleolus disappears and the centromere migrate to oppiste poles forming the mitotic spindle
    -The nuclear envelop disassemebels
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32
Q

What is the process of Metaphase

A
  • Chromosome fully condenses and aligns at the equatorial plate
  • Kinetchores on chromosomes attatch to spindle microtubules
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33
Q

What is the process of Anaphase

A
  • Sister chromtids seperate and move to opposite spindle poles, now they are considered as individual chromosomes
  • The spindle pores move further apart, aiding chromosome sepearation
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34
Q

What happens in Telopahse

A

-The chromosomes at the spindle poles decondense
-The nuclear envelope re assembles around each chromsom set

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35
Q

What are stem cells

A

A small population of undifferentiated cells in the tissues

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36
Q

What is the role of stem cells

A
  • They enable the renewal of differentiated cells through an individuals life
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37
Q

Where are stem cells located

A

-In specifc microevironments , or niches that maintain their undifferentiate state

38
Q

Where are the stem cells studied

A

In rapidly renewing tissues, such as blood, skin and the digestive tract

39
Q

What is meiosis and what does it involve

A
  • Cell division process that prduces halpoid gametes(sperm+egg) from diploid percursor cell
  • It involves 2 cell divisions, resulting in 4 geneticically unique haploid cells
40
Q

Explain the key feature of meisois:
- Synapsis + crossing over

A

SYNAPSIS + CROSSING OVER
- Where the homologus chromosomes pair up in a process called synapsis, allows for crossovers to occur
- The mixing of the genetic material produces new gene combinations, increasing the genetic diversity

41
Q

Explain the the key feature
- Haploid cells
in meiosis

A
  • This is the result of meiosis with half of the usual chromosome number
  • This then combines during fertilisation to form a new dilpid zygote
42
Q

What stages of Meiosis

A
  • Prophase 1
  • First Meiotic division
  • Second Meiotic Division
43
Q

What happens in the first stage of prohpase 1

A

-chromosome condesne , pair up , and undergo sypnapsis
- Crossing over occurs, promoting genetic variation

44
Q

What happens in the first meiotic division?

A
  • ## Homologus chromosomes seperate into new cells, each are still diploids but with paired chromatids
45
Q

What happens in the third stage of meiosis

A
  • Chromosomes seperate without DNA replication , forming halpoid cells with single chromatids each
46
Q

What is the difference between Meiosis and Mitosis

A

Mitosis:
- Produces 2 genetically identical diploid cells
- No genetic variaton( no crossing over or recombination)
Meiosis:
Produces 4 genetically different/unique halpoid cell

47
Q

Which components are in the Nucleus?

A
  • Nuclear envelope
    -Chromatin
  • Nucleoli
48
Q

1.What is the Nuclear envelope?
2. What is the structure of the Nuclear envelope?

A

1- It is a selectively permeable membrane that acts as a boundary between the nucleus and cytoplasm
2- Has 2 membranes, separated by a perinuclear space

49
Q

What is the inner membrane of the nuclear envelope supported by ?

A
  • Nuclear lamina which is a protein network that stabilises he envelope
50
Q

What is Apoptosis

A
  • hIghly regulated process of programmed cell division
51
Q

What is the role of Apoptosis

A

It eliminated defective and unneeded cells without causing inflammation

52
Q

What is the mechanism of Apoptosis

A

It is controlled by Bcl-2proteins
- The proteins regulate the release of death-promoting factors from mitochondria
- They are activated by external signals or irreversibke internal damage

53
Q

Name the four basic cell types

A

-Epithelial tissue
-Connective tissue
- Muscle tissue
- Nervous tissue

54
Q

What components do organs consist of and their function?

A
  • Parenchyma: responsible for organs specialised fucntions
  • Stroma: supports connective tissue
55
Q

Name the 3 functions of the epithelial cell with a brief explanation

A
  • Protection( supports and protects the surfaces)
  • Absorption( Faciliatates nutrient uptake)
  • Secretion(produces and releases substances)
56
Q

What are three shapes epithelial cells can have?

A

Columnar
Cuboidal
Squamous

57
Q

Explain the shape of the nuclei in the columnar, cuboidal or squamous cells

A

Elongated in columnar cells
Flattened in squamous cells
Spherical in cuboidal cells

58
Q

What is the function of the basal pole and the apical pole?

A

Basal pole: Contracts ECM and the connective tissue
Apical pole::Faces an open space

59
Q

Explain epithelial nutrient supply

A

-Epithelial lack blood vesselsand depend on on nutrients and oxygen from adjacent connective tissues

60
Q

What is Laminate propria.

A

Connective tissues underlying the epithelia

61
Q

What is the function of the basment membrane in the Epthelial cells

A
  • Provides structural support
  • Maintains epithelial polarity
  • Facilitates epithelial repair
  • Regulates molecular filtration
62
Q

What is the basment membrane

A
  • A thin extracellular sheet supporting the epithelial cells
  • Acts as a semipermeable filter for substances
63
Q

How does the basment membrane look in the TEM

A
  • It is visible under 2 layers.
  • basal lamina
  • Reticular Lamina
64
Q

Where is the tight (occluding) junctions

A
  • Located at the apical end forming a seal between cells
    composed of claudin and occluding proteins
65
Q

What are the functions of the tight junctions

A
  • Prevent paracellular transport
  • Main distinct apical and baso lateral membrane domains
66
Q

What are Adheren junctions

A

Encircle cells below tight junctions

67
Q

What is the function of Adherene junctions

A

-Provides mechanical strength and links to a cytoskeleton

68
Q

What is the function of desmosomes junctions

A

Provide firm adhesion and resilience against mechanical stress
- Attach the epithelial cell with the basal membrane

69
Q

What is the function of gap junctions

A
  • Allow the exchange of ions and small molecules
  • Enable intracellular communication
70
Q

What is the structure and function of microvilli?

A
  • Small uniform cytoplasmic projections
    Covered by glycoalyx containing enzymes for digestion
71
Q

What does microvilli contain(components)

A

Contains bounded actin filaments , stabilised by actin-binding proteins

72
Q

What is the structure of stereocilia?

A
  • It is longer and less motile than microvilli
73
Q

Where are stereocilia found?

A
  • In male reproductive systems and the inner ear
74
Q

What are the components of stereocilia?

A

Have actin filaments connected o the terminal web

75
Q

What is the function of the cilia( motile and non motile)

A

Motile:Generates fluid movement along the epithelial surface
Non motile: detect environmental signals

76
Q

Where is the flagella found?

A
  • Found in sperm cells
77
Q

What is the function of the flagella

A

Enables movement

78
Q

What dose chromatin consist of

A
  • DNA and associated proteins
79
Q

What is the function of Nuclear pores?

A

Facilitate the movement of ion, molecules and macromolecules

80
Q

Name the types of Chromatin

A
  • Eurochromatin
    -Heterochromatin
81
Q

Explain heterochromatin

A
  • Dense, transcriptinally inactive includes:
  • Constitutive heterochromatin
  • Facultative heterochromatin
82
Q

Explain eurochromatin

A
  • Lightly stained , transcriptionally active
83
Q

Cells with more eurochromatin are ……

A

Metabolically active

84
Q

Cells with more hetero eurochromatin are……..

A

Less active

85
Q

what is it called when the basement membrane of the epithelial cell has one cell layer and describe the cells shape

A

Simple
cells off simple epithelia are either squamos, cuboidal, or columnar

86
Q

What is epithelia called with 2 or more layers of cells and the shape

A
  • Stratified
    Mostly all of the stratified epithelia are stratified squamos
87
Q

What is the function of the stratified squamos epithelia

A
  • Move from the basal to the surface layers
  • become filled with keratin intermediate filaments
88
Q

Name an exmaple of stratified squamos epithelia and its function

A
  • Epidermis
  • Covers the body surfaces
  • protects the underlying tissues from excess water loss
89
Q

What is the functions of Macrophages?

A

-Specialize in phagocytosis
-Secrete growth factors critical for tissue repair and regeneration
-Play a role in antigen processing and presentation for lymphocyte activation.
-Abundant at sites of inflammation and involved in tissue repair.

90
Q

What are the characteristics of Macrophages: Nucleus, surface and Cellular structure

A

Nucleus:
- Oval or kidney shaped
Surface:
- Irregular with pleats and protrusions, aiding pinocytotic and phagocytic activity
Cellular Structure:
- Contains well developed Golgi Apparatus and
many lysosomes

91
Q

Where do Macrophages orgiinate from?

A

-

92
Q

Where do Monocytes form?

A

-Monocytes form in the yolk sac during early embryonic development and become part of the mononuclear phagocyte system

Medicine Sem 1 (18 decks)

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