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Nutrition Semester 1 > BMS1060: Cell division/death and connective tissue > Flashcards

BMS1060: Cell division/death and connective tissue Flashcards

1
Q

What are the different phases of the cell cycle?

A

M phase - mitosis and cytokinesis

Interphase:
G1 phase - cell growth
S phase - DNA replication - chromatin proteins produced
G2 phase - cell growth

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2
Q

Name the stages of the M phase.

A

Prophase
prometaphase
Metaphase
Anaphase
Telophase

Cytokinesis

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3
Q

What is cohesin?

A

Cohesin is a protein complex that holds sister chromatids together. It is in the form of a ring - encircling the sister chromatids.

Cohesus disintegrates during metaphase to allow sister chromatids to separate and move to opposite poles of the cell in anaphase.

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4
Q

What occurs in prophase?

A

Replicated chromosomes condense. Mitotic spindles assemble between the two centrosomes (outside nucleus).

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5
Q

What occurs in prometaphase?

A

Breakdown of nuclear envelope. Chromosomes attach to spindle microtubules via kinetochores.

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6
Q

What occurs in metaphase?

A

Chromosomes line up along the equator of the spindle. Kinetochore microtubules attach sister chromosomes to opposite poles of spindle.

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7
Q

What occurs in anaphase?

A

Sister chromatids synchronously separate to form two daughter chromosomes - each pulled towards the spindle poles it faces.

Kinetochore microtubules get shorter, and the spindle poles also move apart.
Contributes to chromosome segregation.

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8
Q

What occurs in telophase?

A

Two sets of daughter chromosomes arrive at the poles of the spindle and decondense.
New nuclear envelope reassembles around each set.
Division of cytoplasm begins.

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9
Q

What occurs in cytokinesis?

A

Cytoplasm is divided by a contractile ring of actin and myosin filaments - producing 2 daughter cells (1 nucleus, 1 centrosome, share of all organelles)

DNA decondenses and cells return to resting interphase G1.

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10
Q

What is included in the actin cytoskeleton? What does it do? What happens to it during mitosis?

A

Actin cytoskeleton -> Actin filaments, accessory and regulatory proteins.

Can produce protrusive and contractile forces - defining cell shape.

During mitosis, actin cytoskeleton is dismantled and rearranged.
At end of mitosis, actin rearranges - important in separating centrosomes in cytokinesis.

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11
Q

Describe the structure of the spindle

A

Array of microtubules

Kinetochore microtubules attached to sister chromatids via kinetochores.

+ ends of kinetochore binds to large numbers of microtubules.

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12
Q

The cell cycle is based on a series of _____ which initiate specific cell-cycle events.

What are the 3 major regulatory transitions they are involved with?

A

swtiches (on/off)

1) G1/S transition
2) G2/M transition
3) Metaphase/Anaphase transition

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13
Q

What do Kinases do?

A

They catalize phosphorylation (ATP -> ADP + Pi)

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14
Q

What are the main enzymes involved in the cell-cycle control system?

What binds to them to activate them?
What binds to them to inhibit them?

A

Cyclin-depenent kinases

Cyclins

Cdk inhibitor proteins

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15
Q

When does cyclin-dependent kinase activity increase in the cell cycle?

A

At the G2/M transition -> increases phosphorylation of proteins that control events in early mitosis

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16
Q

There are cyclic changes in concentration of _______ throughout the cell cycle, which result in different levels of ________ of cyclin-dependent kinases - causing the different _____ of the cell cycle.

A

Cyclin

Activation

Stages

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17
Q

How is meiosis different to mitosis?

A

There are 2 successive rounds of chromosome separation (separating homologous pairs, then sister chromatids) in meiosis while only 1 round (separating chromatids) in mitosis.

Meoisis produces 4 haploid (1 copy of each chromosome) cells, while mitosis produced 2 diploid (2 copies) cells.

Meoisis has DNA cross-over to from recombinant DNA - increasing genetic diversity - while mitosis doesn’t.

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18
Q

What are bivalent chromosomes?

What is the chiasma?

A

Chromosomes from male and females parents which line up to form exchange points (crossing over).

Chiasma = point of crossing-over

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19
Q

Name the 5 stapes of meiotic prophase

A

Leptotene
Zygotene
Pachytene
Diplotene
Diakenesis

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20
Q

What is histology?

A

The study of tissue and cells - by cutting,
staining and examining under a microscope.

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21
Q

What is used to stain samples in histology?

A

H&E

Haematoxylin - basic dye that binds to acidic components (DNA and RNA)

Eosin - acidic dye that binds to basic components (proteins in cytoplasm).

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22
Q

What are two types of epithelial tissue?

A

Epithelia - layers of cells covering internal and external surfaces

Glands - structures that produce secretions

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23
Q

What are the functions of epithelial tissues?

A
  1. Provide protection
  2. Control permeability
  3. Provide sensation
  4. Absorb nutrients
  5. Secretion
  6. Transport (e.g. ciliated epithelia)
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24
Q

What are the characteristics of epithelial tissue?

A

PARAS:

POLARITY- basal and apical surfaces

ATTACHMENT - via basal lamina to underlying connective tissue.

REGENERATION - replacing lost cells via cell division from stem cells

AVASCULARITY - no blood vessel -> diffusion

SPECIALISED CONTACTS - cell junctions, closely packed cells

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25
What do apical and basal surfaces come in contact with?
Apical - outside environment/internal cavity Basal - basement membrane
26
What benefit comes from epithelial tissues having specialised contacts? Give examples of these contacts.
Increases strength and impermeability - makes cells hard to pull apart.
27
What is the function of the Basal lamina and Reticular lamina? (both part of the basement membrane)
Basal Lamina - selective filter Reticular Lamina - gives basement membrane its strength
28
How do you classify Epithelial tissue?
Number of cell layers: - simple (one) - stratified (many) Cell shape: - Squamous (flat) - Cuboidal (cube) - Columnar (column)
29
What is the function and location of the simple and stratified SQUAMOUS epithelium?
SIMPLE SQUAMOUS - diffusion and filtration - lung alveoli and capilaries STRATIFIED SQUAMOUS - protection - lining esophagus, mouth and vagina. Kertinized type (contain keratin) in skin epidermis etc.
30
What is the function and location of the simple and stratified CUBOIDAL epithelium?
SIMPLE CUBOIDAL - secretion and absorption - kidney tubules, ducts and secretory portions of small glands STRATIFIED CUBOIDAL (generally two layers) - secretion - lumen of glands (e.g sweat glands)
31
What is the function and location of the simple and stratified COLMNAR epithelium?
SIMPLE COLUMNAR - absorption, secretion and movement (ciliated types) - digestive tract, ducts of some glands, ciliated respiratory tract and uterous STRATIFIED COLUMNAR (basal cells cuboidal and superficial cells columnar) - protection and secretion - large ducts of glands and urethra
32
What are the two extra unusual classes of epithelial tissue? Where are they found?
PSEUDOSTRATIFIED COLUMNAR EPITHELIUM - seems stratified columnal, but actually simple. - secretes and moves (usually mucus) - male reproductive tract and respiratory system TRANSITIONAL EPITHELIUM - surface cells dome shaped/flat. Basal cells cuboidal/columnar - stretches to permit distension of bladder - lines urinary bladder
33
What do glands have a lot of?
ER, golgi apparatus and secretory granules.
34
How are glands classified?
ENDOCRINE (hormones enter blood/lymphatic fluid) VS EXOCRINE (hormones secreted on skin or in body cavities/ducts) Unicellular / multicelluar
35
Describe the goblet cell - what kind of gland is it? Where is it found? What does it secrete?
Unicellular Exocrine Gland Found in linings of digestive and respiritory tracts. Secretes mucin which dissolves in water to form mucus. Mucus protects (from microorganisms, digestive enzymes, dust particles etc) and lubricates sufraces.
36
Describe multicellular exocrine glands.
Composed of duct and secretory unit. Formed by invagintion of epithelium. Connective tissue provides support and nutrients to glands. Classified by mode of secretion.
37
What are the 3 modes of secretion of exocrine glands?
MEROCRINE GLANDS - secrete by exocytosis APOCRINE GLANDS - a portion of plasma membrane buds off cell containing secretion. HOLOCRINE GLANDS - entire cell disintegrates to secrete product.
38
Why is cell death important? Any cons?
It maintains tissue homeostasis and eliminates harmful cells. Homeostasis -> Balance between cell growth, division and death Cons: - Killing wrong cells (e.g. neurodegeneration) - Failing to kill cells generated in excess (cancer)
39
What are the 2 main types of cell death? Briefly describe them
Necrosis and Apoptosis NECROSIS - accidental cell death Cells swell and burst. Contents released -> inflammation. APOPTOSIS - Programmed cell death. Cells engulfed and digested. Energy (ATP) dependent.
40
What are the 3 other types of cell death?
AUTHOPHAGY - degradation of unneccesary/dysfunctional cellular components. FERROPTOSIS - triggered by accumulation of lethal ROS in cells. NECROPTOSIC - form of necrosis - triggered by viral loads.
41
What is the role of apoptosis?
For tissue structure (e.g. hands and feet development) When structure is no longer needed (tadpole -> frog) Quality control - eliminating abnormal cells Destroying cells that are threats to an organism.
42
Describe the process of Apoptosis
1. Stimulus - > cell shrinks, chromatin condenses. 2. Membrane starts blebbing. Organelles disintegrate. 3. Nucleus and organelles collapse. Membrane continues to bleb. 4. Apoptotic bodies form. 5. Macrophages phagocytose apoptotic bodies.
43
What are Caspases?
Proteases that cleave specific proteins at specific AA sequences. (Particuarly at aspartic acids). Not all caspases are involved in Apoptosis (11 different caspases)
44
What are the two major classes of apoptic caspases?
Initiator and Executioner caspases (initiator caspases trigger executioner caspases)
45
Briefly describe the mechanism of Initiator caspases.
Inactive initiator caspase monomers --Apoptotic signal--> Activated initiator caspase --(cleavage)--> mature active initiator caspase
46
What is a dimer?
A chemical compounds consisting of two or more protein monomers
47
Executioner caspases: - what activates them? How? - what does activation of one E-caspase lead to?
Activated through cleavage by initiator caspases. Once activated, they cause widespread cleavage of proteins - killing cells and preparing them for engulfment and digestion. This process is irreversible.
48
What are the two activation pathways for initiator caspase?
Extrinsic - signal from outside of cell Intrinsic - signal from inside the cell Each uses its own initator caspases.
49
What type of receptors are found in the extrinsic pathway for initiator caspase?
Death receptors Signal proteins from outside of cell bind to these to trigger the apoptotic process.
50
What induces the intrinsic pathway for initiator caspase?
Cytochrome C (mitochondrial protein released from intermembrane space into cyctosol). This initiated adaptor protein, which recruits caspase monomers an apoptosome.
51
What is osteoporosis?
A progressive systematic skeletal disease characterized by LOW BONE MASS and MICRO ARCHITECTUAL DETERIATION of bone tissues, leading to increased BONE FRAGILITY and susceptibility to fractures.
52
What is the difference between Osteoclasts and Osteoblasts?
Osteoclasts - create resorption cavities - breakdown bones. Osteoblasts - make bone matrix which is then mineralised - build up bones.
53
How does bone density differ according to age? What can be done to reduce bone density loss?
Increase calcium, protein and vitamin D intake. Increase excercise. Decrease alcohol and smoking.
54
The body has mechanisms to keep Ca levels balanced and stable called ________ ___________. If this fails this can lead to __________ or __________. Vitamin __ plays a vital role in calcium absorbtion.
Calcium homeostasis Hypercalcium or hypocalcum Vitamin D
55
What is used to measure bone density? What are the levels we need to know? What should blood pH level be at? What do you use to measure vitamin D? What does deficiency lead to?
Above -1 = normal -1 to -2.5 = Osteoperia Below -2.5 = Osteoporosis normal blood pH = 7.4 Vitamin D is measured using 25 OHD status. Deficiency -> Rickets in children, osteoporosis or osteomalacia in adults
56
Give some examples of connective tissue diseases.
- Perivascular collagen deposition / collagen vascular disease - Autoimmune diseases Exact causes remains obscure. Different diseases associated with specific antibodies
57
Describe smooth muscle - what types of cells are formed? - how many nuclei? - striated? - voluntary? - how fast are contractions?
- Fusiform cells (long, interlocking, spindle-like) - 1 Nucelus per cell - Non-striated - Involuntary - Slow, wave-like contractions
58
Describe cardiac muscle - what types of cells are formed? - how many nuclei? - striated? - voluntary? - how fast are contractions?
- Branching cells - 1/2 nuclei per cell - Striated - Involuntary - Medium speed contractions
59
Describe skeletal muscle - what types of cells are formed? - how many nuclei? - striated? - voluntary? - how fast are contractions?
- Long cyndrical cells - Many nuclei per cell - Striated - Voluntary - Rapid contractions
60
What are the 'muscular' terminologies for cell membrane, cytoplasm and muscle cells?
Cell membrane = Sarcolemma Cytoplasm = Sarcoplasm Muscle cells = Fibres
61
What is the difference between fast and slow twitch muscle fibres?
FAST: - high force - low endurance - fast myosin ATPase - uses O2 - high capillary density - high mitochondria density SLOW: - low force - high endurance - slower myosin ATPase - anaerobic respiration - high glycolytic capacty
62
What are the functions of muscle?
Movement Heat production Maintenance of posture and balance Protects bones and internal organs
63
Label the sections of this muscle fibre
64
What does a smooth muscle contraction look like?
65
What type of microscopy can be used to view cell junctions?
Freeze fracture electron microscopy
66
What are the 3 classifying groups of cell junctions?
Occluding or Tight junctions Anchoring Junctions Communicating Junctions
67
What do occluding/tight junctions do? What makes these junctions 'tight' or 'leaky'? What proteins are they formed by?
They seal epithelial cells tightly together to prevent molecules leaking from one side to the other. 'tight' (e.g. blood-brain barrier) or 'leaky' (kidney tubules) depending on number of junctions. Formed by Claudin or Occludin proteins.
68
What do anchoring junctions do? What are some examples?
- They mechanically attach cells to their neighbouring cells or extracellular matrix. - They provide the tissue with strength. - They help to form glands. Examples: CELL TO CELL Adherens junctions and desmosomes CELL TO EXTRACELLULAR MATRIX Hemidesmosomes and Focal adhesions
69
What do desmosomes and hemidesmosomes anchor to?
Both anchor to intermediate fillaments. Desmosomes connect cell to cell. Hemidesmosomes connect cell to extracellular matrix.
70
What do Adheren junctions and Focal adhesians anchor to?
They anchor to actin filaments. Adherens - link cell to cell. Focal - link cell to extracellular matrix
71
What do communicating junctions do?
They mediate the passage of small molecules from one cell to the next. - ions, vitamins and metabolites but NOT macromolecules (protein, RNA etc) This allows chemical and electrical transmission between cells.

Nutrition Semester 1 (11 decks)

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