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Human Anatomy and Physiology > Week 2 Module 1 > Flashcards

Week 2 Module 1 Flashcards

1
Q

What is the purpose of the Cell Membrane?

A

It encapsulates the cell, being protective from the external environment and being invloved in communication with other cells.
It ensures the cell’s structural integrity and maintains the chemical composition of the inside cell and extracellular space by allowing entry and exit of certain substances.

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2
Q

What does selectively permeable mean in the cell membrane?

A

Various particles are allowed to freely move in and out the cell while others are restricted and require active transport.

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3
Q

What is the structure of a phospholipid?

A

The head is made of a phosphate group and glycerol molecule, being hydrophilic.
The tail is a lipid made of two fatty acids that are hydrophobic.

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4
Q

What does the phospholipid bilayer seperate?

A

The extracellular and intracellular content in an organism.

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5
Q

What is a glycoprotein?

A

Carbohydrate attached to a protein.

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6
Q

What is a glycolipid?

A

Carbohydrate attached to a lipid.

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7
Q

What are some types of cell membrane proteins?

A

Peripheral membrain protein: only on periphery.
Integral membrain protein: spans whole membrane. Eg. protein channels that allow exchange of molecules.

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8
Q

What does cholesterol do in the cell membrane?

A

It help maintain structural integrity and rigidity.

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9
Q

What do filaments of the cytoskeleton do to the cell membrane?

A

Anchor, stabilise, and position the membrane to the external environment.

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10
Q

What are the classifications for Plasma Membrane proteins?

A

Anchoring proteins,
Recognition proteins,
Receptor proteins,
Carrier proteins,
Enzyme proteins,
Identification.

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11
Q

What do anchoring proteins do?

A

Enable cell membrane to interact with cytoskeleton and external cell structures to stabilise.

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12
Q

What do recognition proteins do?

A

Identification system, they help immune system and other cell types with identification. (glycoprotein/lipid combination)

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13
Q

What do receptor proteins do?

A

Sit on the surface of the membrane and bind to ligand molecules. They have very specific structure (ligand as well). Ligands carry a message, binds, and the message is transmitted to the inside.

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14
Q

What do carrier proteins do?

A

Bind molecules and allow them to transport across the membrane.

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15
Q

What do channel proteins do?

A

They are integral, and can open and close based on signals, allowing entry and exit of substances in large volumes.

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16
Q

What do enzyme proteins do?

A

Speed up chemical reactions.

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17
Q

What is the identification system in a cell?

A

Proteins present on cell membrane act as chemical markers showing what they are, age, disease, etc.

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18
Q

How do small, uncharged, hydrophobic molecules pass through the membrane?

A

They can freely pass through the membrane through diffusion (eg O2).

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19
Q

How do small, uncharged, polar molecules pass through the membrane?

A

Some can diffuse through the membrane others with a transport protein.

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20
Q

How do large, uncharged, polar molecules pass through the membrane?

A

Need assistance of carrier/transport proteins.

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21
Q

How do ions pass through the membrane?

A

Cannot pass through the membrane without protein channels.

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22
Q

What does it mean if a molecule can enter the cell using simple diffusion?

A

It can freely enter and exit the cell, and is non-threatening.

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23
Q

How can water enter the cell?

A

Osmosis or an aquaporin (both are passive).

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24
Q

What is cellular communication?

A

The transfer of concise information sent effectively.
Breakdown in communication can lead to problems.
Eg. Organs need to communicate with others to function properly and carry out homeostasis.

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25
What happens in cellular communication?
A signalling cell releases a signal after reacting to a stimulus. This is received by the target cell, generally being processed in the nucleus. The cell will then undergo the required specialised function (eg cell division, differentiation).
26
What does cellular communication rely on, and what are the two types of signalling?
It relies on ligands and receptors. There is direct (cell to cell) and indirect signalling.
27
What are ligands?
Extracellular chemical molecules that exist in the extracellular environment.
28
Why do receptors and ligands need to be complimentary?
There is a messenger released by a secretary cell that is sent to the target cell, finding its complimentary receptor on the cell/cell membrane. If the specificity does not match, no communication will occur.
29
Are there many receptors on the cell membrane?
There is a large amount.
30
What are ligands secreted from - what are they?
Ligands are secreted from secretory cells and are eitehr proteins, lipids, or ions.
31
What are the two distances ligand communication can be?
Local or long distance.
32
What can hydrophobic ligands do?
They can pass through the plasma membrane and bind to intracellular receptors. Generally hormones.
33
What can hydrophilic ligands do?
Not pass through the plasma membrane, thus binding to extracellular receptors on the membrane to elicit a response. Generally peptides and small proteins.
34
What are receptors?
Proteins on the surface of the cell that may span entire length of the membrane. They exist to bind to ligands.
35
What is important to receptors and ligands?
They are both highly specific and need to math each other both structurally and chemically to prevent cell confusion.
36
What can ligands do?
Elicit different reactions in different cell types due to different signalling molecules inside the cell.
37
What are the four types of recelptor proteins?
Ligand-gated ion channel, Enzyme-linked receptor, G Protein-coupled receptor, Intracellular recetor.
38
Explain the ligand-gated ion channel.
The surface of the channel has a ligand binding pocket, causing a change in shape that opens the channel and lets ions enter the cell, changing the concentrations within the cell.
39
Explain the enzyme-linked receptor.
Physically associated with an enzyme. LIgand binds to receptor, inducing a change of shape, leaving to activation of the associated enzyme and leading to a chemical reaction. The signal is then sent to the centre of the cell.
40
Explain the G protein-coupled receptor.
There is a mediator (G-protein) that communicates between the receptor and enzyme Responsible for activating multiple chemical reactions, leading to amplification of the signal. Typically involved in the immune system and inflammation.
41
Explain intracellular receptors.
Found generally in the cytoplasm, but also the nucleus. The ligand is generally hydrophobic and can easily cross the plasma membrane. binding to the intracellular receptors and forming a ligand-receptor complex. This binds to DNA, resulting in transcription and then translation.
42
What are the types of cellular signalling?
Direct cell signalling and indirect signalling. Indirect signalling is split into Autocrine signalling, Paracrine signalling, and Endocrine signalling. Grouping depends on distance signals travel.
43
What is direct communication?
Cells are joined together through gap jumptions - porous protein tunnels that physically join teh membranes together, allowing the cytoplams to be joined. As a result, ions and water soluble molecules can be transferred between cells.
44
When is direct communication seen between cells?
When there are groups of cells that need to react at the same time. (eg. heart contraction).
45
What is autocrine signalling?
When cell producing the signal feeds the signal back to itself, inducing a response.
46
When is autocrine signalling seen?
In embryonic development or in cells infected with a virus (can induce cell suicide).
47
What is paracrine signalling?
Cells are close together, one releases ligands that bind to te receptors of the other, inducing the required response. The responses are short lived and very quick.
48
What is endocrine signalling?
Long distance, one cell releases a cell signal that travels through the blood stream. It results in a slow response with a long lasting effect.
49
When are endocrine responses seen?
In the endocrine system. Generally, secretory cells involved are endocrine glands.
50
What determines a cellular response?
The ligand, type of receptor, and the signalling molecules present in the cell dictate what signal is relayed to the nucleus.
51
What are extracellular receptors?
Receptors that sit on the plasma membrane. Generally work with making the cell undergo: growth, differentiation, proliferation, movement/migration, and death/survival.
52
What is the distance between extracellular and intracellular receptors?
Intracellular rece[tprs require no activation of other signalling molecules.
53
How are all cells in the body produced?
Through cell division. One fertilised cell ends up as 30-40 trillion cells.
54
Why is cell division done?
For growth and development, renewal and replacement, and regeneration and repair. Different cells have different life spans.
55
What are the 2 types of cell division and where do they occur?
Mitosis: occurs in somatic cells or adult cells. Meiosis: specific to gametes or the cells of the reproductive system.
56
What is the cell cycle?
Cells have a life cycle made of different phases of growth and maturation. A typical cell cycle is largely made up of interphase. If not, it is usually actively dividing and undergoing mitosis.
57
What is interphase in the cell cycle?
The time when cells develop and grow, utilising their nutrients to make energy. Proteins are synthesised and they exercise assigned functions while preparing for mitosis. It can be split into g (growth) and s (synthesis) phases. Overall, organelles are doubled and DNA is ready to duplicate.
58
What happens in G1+2 and S phases?
In G1+2, the cell grows, synthesises proteins, makes more cytosol, and replicates its organelles. In S phase, DNA is duplicated and paired to allow for seperation in mitosis.
59
What does the cell cycle having discrete phases allow?
For checkpoints to make sure everything is going to plan, and to abort/fix anything if necessary. It makes sure and checks everything required has been synthesised or copied adn that DNA can be equally distributed among daughter cells.
60
What happens when cell division is to occur in the cell cycle?
The cell enters mitosis, where the duplicated DNA is seperated to hte two poles of the cell and forms 2 daughter cells after cytokinesis ocurs. Takes 1-3 hours.
61
Explain G1 (gap) phase.
Normal cell function, organelles are getting regenerated and duplicated. Takes 8-12 hours.
62
Explain S (synthesis) phase.
DNA is being replicated, nuclear proteins and histones are synthesised to duplicate the chromosome. Takes 6-8 hours.
63
Explain G2 phase.
Final protein synthesis, centrioles are replicated. (the organelles that control positions of stuff in the cell).
64
Explain G0 phase.
After daughter cells are formed, cell becomes dormant and focuses on normal cell function.
65
How does a cell enter mitosis and how does it leave?
A cell enters mitosis as one cell filled with double the content and leaves as two identicle cells.
66
What are the stages of Mitosis?
Prophase, Metaphase, Anaphase, and Telophase. It ends with Cytokinesis.
67
What happens in early prophase?
DNA packed into chromatin disperses within the nucleus, and then further condenses, becoming highly compact. The doubled compacted DNA arranges itself into identical sister chromatids that join at the centromere and form a chromosome.
68
How are sister chromatids joined?
By the kinetocore (kinetocore proteins?) in the centromere.
69
What happens in late prophase?
Formation of the mitotic spindle is finished: the centrosomes that were copied in G2 move to opposite ends of the cell and the nucleus disintegrates with the nuclear envelope fragmenting, allowing movement of DNA within the cell. This also allows the microtubutes to connect to both the centrosomes and the kinetochores at both poles.
70
What is a mitotic spindle?
The spindle is a network of protein filaments (microtubule like in the cytoskeleton). The spindle appears to grow from a centrosome - an organelle consisting of two centrioles.
71
Difference between centromere and centrosome.
Centromere joins two chromatids together, centrosome is two centrioles that makes up the mitotic spindle.
72
What occurs in Metaphase?
The chromosomes line up against the equator. Each kinetochore is binded to a centriole by microtubules.
73
What occurs in anaphase?
THe chromosomes are split into the sister chromatids, respective chromatids more along the spindle fibres to opposite ends of the cell.
74
What occurs in telophase?
The respective groups of chromatids seperate and a new nuclear membrane is fored, allowing the DNA to uncondense to chromatin.
75
What occurs in cytokinesis?
Cell membrane pinches at the centre of the elongated cell, seperating it into two identical daughter cells.
76
Around what amount of the cell cycle is taken up by interphase?
3 quaters.
77
What does chromatin look like as DNA condenses?
It appears to darken.
78
What are the main 3 checkpoints in the cell cycle?
G1, G2 and M. These checkpoints ensure the cells are healthy and functional, ready to divide.
79
What occurs in the G1 checkpoint?
Ensures there is enough energy stores available for division, assesses DNA for errors.
80
What occurs in the G2 checkpoint?
Ensures DNA is correctly replicated and completed.
81
What occurs in the M (Mitosis) checkpoint?
Assesses DNA and that chromatids are attached to microtubules.
82
What happens if there is an error in a cell cycle checkpoint?
It looks for errors and breaks and then attempts a repair. If repair is impossible, the cell undergoes apoptosis. (cell death)
83
What is p53?
A protein in the cell cycle that ensures DNA integrity. It scans DNA for mutations, breaking, etc. Identifies it and initiates repair (activates DNA repair pathway). Causes cell cycle arrest until everything is fine.
84
What happens if p53 cannot repair the DNA?
It initiates programmed cell death.
85
What is the most commonly mutated protein in cancers?
Around 60% - p53 mutations. The other 40% are genes involved with p53.
86
What does p53 do?
When DNA is exposed to an antigen, it causes breaks in the DNA - detrimental to the cell. p53 binds to the DNA to find breaks and can then activate DNA repair enzymes.
87
What is seen when apoptosis is unable to occur?
Diseases like cancer. - There are primary mutations that accumulate until the cellgrows out of control.
88
What are the two types of cell death?
Apoptosis and Necrosis.
89
What is apoptosis?
Programmed cell death, coordinated by a number of genes that initiate apoptosis coordinatedly.
90
What is necrosis?
Unplanned cell death, not initated by the cell. Occurs due to external stressors.
91
What are the causes of apoptosis?
Physiological: used by the body for the body plan. Cell turnover: When a cell reaches the end of its life span and needs to be replenished. Development Hormone regulated tissues N.E. intrinsic vs extrinsic.
92
What is the process of apoptosis?
Cell shrinkage and nuclear condensation - DNA packed into chromatid structures. Blebbing of the cell membrane as the cell becomes fragmented. Phagocytes enguylf the fragments ensuring no inflammation - cleared by macrophages.
93
What causes necrosis?
Pathological - due to external stimulus or injury Can be mechanical, chemical, infection, and immune responses.
94
What is the process of necrosis? part 1. end with condense
The cell swells due to organelles swelling. Cytoplasm is packed with vacuoles. Ions and water enter the cell causing swelling. There is blebbing and the cell becomes fragmented. The nucleus shrinks and DNA condenses into heterochromatin.
95
What is the process of necrosis? part 2. starts with chromatin.
Chromatin disperses into the cytoplasm after the nucleus fragments. Cell ruptures, releasing content into the extracellular environment, resulting in inflammation as the immune system reacts.
96
Is cell death reversible?
Yes, but only up to a certain point.
97
What are the necrosis types?
Coagulative necrosis, liquefactive, caseus, gangrenous.

Human Anatomy and Physiology (3 decks)

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