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Foundation Year MBChB > Principles of Human Cell Biology > Flashcards

Principles of Human Cell Biology Flashcards

1
Q

What is one of the key concepts of human biology?

A

That everything derived from one cell and human biology stems from a group of cells

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2
Q

What are the similarities and differences between prokaryotic cells and eukaryotic cells?

A

Prokaryotes:
No membrane-bound organelles
DNA in a nucleoid, not separated from the rest of the cell
Single-celled
Circular DNA with no introns
Smaller

Eukaryotes:
Has membrane-bound organelles
DNA separated from the rest of the cell in the nucleus
Can be single-celled or multicellular
Chromosomal DNA with exons and introns
Larger

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3
Q

Why are viruses not considered living?

A

They are acellular, they cannot undergo metabolic reactions and they don’t replicate on their own

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4
Q

Approximately how many time larger is a eukaryotic cell compared to a prokaryotic cell?

A

Approximately over 20 times (at least 50)
50µm eukaryotic cell
1µm prokaryotic cell

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5
Q

What are the two major forms of prokaryotes?

A

Bacteria and archaea

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6
Q

What are distinct features of a prokaryotic cell?

A

Prokaryotes have a smaller genome and a single, circular genome
They may also have plasmids, small sections of circular DNA which can be passed between cells
They do not have membrane-bound organelles (such as a nucleus)

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7
Q

What does viral genetic material force cells to do once injected into the cell?

A

Make/copy the viral DNA and RNA
To produce viral proteins

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8
Q

Why does viral replication negatively affect host cells?

A

The host cells eventually burst as too many viral proteins have been replicated

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9
Q

What are the four major kingdoms regarding eukaryotes?

A

Animals
Fungi
Plants
Protists

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10
Q

How are animal cells defined?

A

By what they lack:
Lack of cell wall
Lack of chloroplasts
Always multicellular

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11
Q

What do eukaryotic cells have to support their function?

A

All eukaryotic cells have organelles to support their cellular function. The organelles include a nucleus, mitochondria, Golgi body, and both smooth and rough endoplasmic reticulum

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12
Q

Why are many supporting structures like ribosomes, not considered organelles?

A

They lack complexity and/or have no membrane

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13
Q

In which way could you describe the appearance of a cell?

A

The cell is surrounded by a membrane (plasma/cell membrane) and contain many membranes in it due to individual organelles, and an endomembrane system

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14
Q

What is an endomembrane system?

A

A group of membranes and organelles in eukaryotic cells that works together to modify, package, and transport lipids and proteins

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15
Q

What are some of the several functions that a membrane provides?

A

Compartimentalisation
Communication
Partial permeability, therefore acts as a barrier

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16
Q

Why is it beneficial for the cell membrane surrounding the cell being able to act as a barrier?

A

This then allows for different molecules to pass through and be responsible for cell signaling

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17
Q

What are the three types of membrane proteins?

A

Integral
Lipid-anchored
Peripheral

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18
Q

Where can each type of membrane protein be found<

A

Integral: within the phospholipid bilayer (within the membrane)
Lipid-anchored: attached to lipids that are in the membrane (lipoproteins)
Peripheral: bound intermolecularly to the membrane (e.g. Hydrogen bonds) but isn’t directly covalently bonded to the membrane

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19
Q

What are some features of integral membrane proteins?

A

Amphipathic: has both polar and non-polar regions so has both polar and non-polar regions
Span the membrane
They can be singlepass or multipass (based on how they bond)
They are partially embedded and so are attached to only one side of the membrane

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20
Q

What are some features of lipid-anchored proteins?

A

Protein is found at the membrane’s surface
Found on both membrane surfaces
Lipid is covalently bonded to the protein within the membrane, therefore lipid-anchored

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21
Q

What are some features of peripheral membrane proteins?

A

Lack hydrophobic regions
Don’t interact with fatty acid ends of membrane lipids
Not chemically associated with the membrane
Associated with the membrane surface via intermolecular forces, (i.e. electrostatic attraction, hydrogen bonding) to either the proteins or the polar head groups

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22
Q

What are the functions that the membrane proteins are responsible for?

A

Transport
ATP production
Biotransformation (metabolism)
Receptors
Cell-cell recognition

23
Q

What are the two critical functions of the nucleus?

A

Contains the cell’s hereditary information (DNA)
Co-ordinates and controls cellular metabolic activity

24
Q

How is the nucleus structured?

A

Nucleus consists of nucleoplasm bound by the nuclear envelope
There are two membranes
Inner membrane: surrounds DNA
Outer membrane: continuous with rough endoplasmic reticulum
Pores: regulates passage of RNA and protein

25
Q

What is reticulum Latin for?

A

Net

26
Q

How can the endoplasmic reticulum be described?

A

System of folded, interconnected membranous vesicles
Large flattened sac-like structures (cisternae)
Internal space is called the lumen

27
Q

What are the two types of endoplasmic reticulum?

A

Smooth endoplasmic reticulum: secretes lipids and has no ribosomes
Rough endoplasmic reticulum: secrets proteins and has ribosomes

28
Q

What is the importance of the endoplasmic reticulum?

A

May account for >50% of the cell’s total membrane content
Both types of ER are involved in the synthesis, storage and transportation of biomolecules
Endoplasmic reticulum membrane allows for lipid/proteins to interact with the cell membrane therefore, protein/lipids in the cell membrane

29
Q

How can the Golgi apparatus be described?

A

Large sac-like membranous vesicles, associated vesicles and tubules

30
Q

What is the main function of the Golgi apparatus?

A

Acts as a processing station- involved in packaging and distribution of cell products for internal and external use
Vesicles budding off ER travel and are accepted by Golgi
Vesicles budding off Golgi travel to the cell surface or other organelles, after products have been modified and packaged into vesicles

31
Q

What are vesicles?

A

Membranes similar to plasma membranes
Internally different from cytosolic environment
Mainly used for transport

32
Q

What are the main purposes of vesicles and what are some well known vesicles?

A

Transport vesicles
Secretary vesicles
Lysosomes: contain hydrolytic enzymes (lysozymes) and acids to fuse with faulty/foreign cells to hydrolyse them- the cell material is then reused
Peroxisomes
Vacuoles

33
Q

What is the function of vacuole vesicles?

A

Compartment for storage and transport
Often temporary e.g. Phagosome
Largest cell vacuoles are found in plants
Help to maintain internal hydrostatic pressure
Store nutrients and waste
Increase cell size during growth

34
Q

What is the function of transport vesicles?

A

Move molecules within the cell, i.e. Golgi to mitochondria
Recognise and fuse only with the target membrane
Carry/transport molecules in the lumen

35
Q

What is the function of secretory vesicles?

A

Contain materials to be excreted from the cell
Removal of waste
Release of chemical signals

Two types of vesicle fusion
Full fusion
Kiss-and-run (partial)

36
Q

How can the mitochondria be described?

A

Site of aerobic respiration & energy production(ATP)
Double membrane
Inner membrane folded forming cristae
Area within the cristae is the matrix
Region between membranes is intermembrane space

37
Q

What are some features of the mitochondria?

A

Matrix contains
Enzymes
Ribosomes, so can produce own proteins
DNA
The machinery for producing ATP for the cell
Distribution in cells and in different tissues depend on function of that cell; mitochondria can adapt to the needs of the tissue, e.g. more contractile space so less mitochondria

38
Q

How can the cytoskeleton be defined?

A

Dynamic 3D structure that fills the cytoplasm
Responsible for:
cell movement
cytokinesis (cell division)
organisation of the organelles

Comprised of:
microfilaments
intermediate filaments
microtubules

39
Q

What is differentiation?

A

Cells differentiate to take on specialised roles
Certain sets of genes are activated whilst others are switched off
Gene expression varies between different cells, therefore the cells have different characteristics

40
Q

What are some examples of differentiation?

A

DNA acetylation and DNA methylation

41
Q

How can you define stem cells?

A

Stem cells are cells that have the ability to self-renew and give rise to at least one different cell type

42
Q

What do the different potencies of stem cells describe?

A

The varying abilities of differentiation that a stem cell has

43
Q

What is a progenitor cell?

A

Progenitor cell: General term for a cell that gives rise to a few specific types of cell. May be unipotent or multipotent
Not always considered stem cells, sometimes because they usually can’t self-renew indefinitely

44
Q

What is a totipotent stem cell?

A

A stem cell that can differentiate into any cell type

45
Q

What is a pluripotent stem cell?

A

A stem cell that can differentiate into any cell type apart from placenta cells

46
Q

What is a multipotent stem cell?

A

A stem cell that can differentiate into multiple cell types

47
Q

What is an unipotent stem cell?

A

A stem cell that can only differentiate into one other type of cell (and can self renew)

48
Q

What type of stem cell is a blastomere?

A

Totipotent
Cells coming directly from fertilised zygote
Self-renew and become the entire bod

49
Q

What are features of embryonic stem cells?

A

In the blastocyst (the very early embryo)
Can not become the placenta (rest of the blastocyst does this)
Pluripotent

50
Q

What are features of adult stem cells?

A

Found in the adult body
Responsible for repair and maintenance of tissues
Mostly multipotent, some are unipotent

51
Q

How can you define a specialised cell?

A

Cells become specialised through differentiation
They acquire new structures and features to perform a specific job
Some specialised cells have very unusual features unlike that of many others in the body
Other types of specialised cells still resemble general body cells, but have certain characteristics to perform their particular role

52
Q

What are features of blood cells, and how can they be specialised?

A

Formed in bone marrow from multipotent haematopoietic stem cells
3 main categories
Erythrocytes (red blood cells)
Leucocytes (white blood cells)
Platelets
Example: Erythrocytes
Lack most organelles
Do not contain DNA
Limited repair capabilities and lifespan

53
Q

What are features of brain cells, and how can they be specialised?

A

Self-renewing multipotent stem cells
Located in subventricular zone and hippocampus
Generate 3 basic cell types
Neurons
Astrocytes
Oligodendrocytes
Example: Neurones
Specialised to transmit information
Oldest & longest cells in the body

54
Q

What are features of sperm cells, and how can they be specialised?

A

Spermatogenesis
Haploid spermatozoa develop from germ cells in the seminiferous tubules

Sperm cells are specialised in a number of ways
Head (acrosome & nucleus)
Tail (undulipodium)
Small and thin

Foundation Year MBChB (11 decks)

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