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Biology > Topic 2 > Flashcards

Topic 2 Flashcards

1
Q

The Cell Theory

A
  1. All cells come from parent cells. Multicellular organisms develop from a single fertilised germ cell (the zygote).
  2. The basic components of the cell (nucleus, cytoplasm, mitochondria etc) are repeated in every cell, even free living unicellular organisms. Cells should be of a certain size…
  3. Cells can be taken from organisms and cultured away from the body. In primitive multicellular animals (e.g. sponges) and most plants whole new individuals can be cultured from isolated cells. This power of regeneration is called totipotence. (it can grow into anything)
  4. Cells need to carry out the ‘characteristics’ of life. MRSGREN
  • All living things made from cells
  • Cells are smallest unit of life
  • All cells come from pre-existing cells
  • All metabolic activity occur in cells
  • All cells contain genetic information which is passed on
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2
Q

THE ORGANISMAL THEORY

A
  1. Some organisms (e.g. Fungi) are not divided into cellular compartments = non-cellular. Plants have plasmodesmata = cytoplasmic bridges between neighbouring cells.
  2. Certain cells lack the basic components (e.g. mature red blood cells have no nucleus). Cells in multicellular organisms are highly specialised. Unicellular organisms have a cytoplasm that is not subdivided into cells and should therefore be considered as acellular.
  3. Remove cells from complete multicellular organisms requires elaborate life support systems to keep them alive.
  4. Homeostatic control and co-ordination is required to maintain the whole organism whether it is unicellular or multicellular (specialises and cannot live on its own) - not all cells are ‘acellular’.
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3
Q

Kingdoms

A
  • Plants (autotrophic)
  • Animals (heterotrophic)
  • Fungi (heterotrophic)
  • Archea (H) Bateria (A)
  • Protists (H)
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4
Q

MRSGREN

A
  • Movement: action/change by an organism or part in position or place
  • Reproduction (metabolism): make more of the same kind
  • Sensitivity (response): Detect and sense stimuli and respond
  • Growth: permanent increase in size and dry mass by increase in cell number or size or both
  • Respiration: chemical reaction that break down nutrient molecules to release energy
  • Excretion (homeostasis): Removal of (toxic and) waste products and excess substances
  • Nutrition: taking in, absorption and assimilation of nutrients (organic substances and mineral ions) containing raw materials or energy for growth and tissue repair
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5
Q

Virus

A
  • Do not fit in kingdoms
  • Do not grow
  • No homeostasis
  • No metabolism outside host
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6
Q

Structure of a Virion (a virus particle)

A
  • Inject DNA into cell, cell make copy of DNA, burst when packed of virus and spreads
  • Nucleic Acid: RNA or DNA
  • Capsid: protein coat that surrounds the DNA or RNA in a virus
  • Lipid Membrane: a membrane around the capsid in many kinds of viruses; helps the virus enter cells (“enveloped” viruses; without the membrane, the virus is “naked”)
  • Made of proteins, lipids, and glycoprotein
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7
Q

Stem Cells

A
  • Fertilised egg cell that is totipotem
  • Embryonic stem cells (germ cells) do not read specific information.
  • First cells to develop after fertilisation.
  • Able to divide continually and turn into any type of cell/tissue/organ.
  • Cell contains a full complement of diploid (2n) DNA, each only reads (expresses) certain genes in the code. So different cells have the information to develop and become specialised.
  • A stem cell is able to divide but has not yet expressed genes to specialise to a particular function.
  • Stem cells can be induced to express particular genes and differentiate into a particular type of cell- totipotent.
  • Stem cells can be obtained from a variety of different places including the blastocyte. Adults have some in some organs but is rare. (placenta)
  • Normally copies itself to create pluripotent cells
  • Totipotent: can become any cell type
  • Pluripotent: can become any type except embryonic membrane
  • Multipotent: can become a number of different cell types (White blood cells)
  • Unipotent: can only become one cell type
  • Nullipotent: cannot divide (red blood cells)
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8
Q

Therapeutic Cloning:

A
  • Involved the in-vitro culturing of tissues using patient or donor stem cells
  • Can be used to replace tissue lost in disease, burned skin or nerve cells
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9
Q

Light Microscopes

A
  • Specimens can be alive (electron- vacuum)
  • Faster- slides and usage
  • Cheaper
  • Easier to maintain
  • More colourful, true colours
  • Small and portable
  • Not affected by magnetic fields
  • Wavelength: 400-700 nm (10^-9 m)
  • Maximum res: x1500
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10
Q

Electron microscopes

A
  • Higher resolution
  • Greater magnification
  • Wavelength: 2nm
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11
Q

Real size

A

= Apparent/Magnification

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12
Q

Conversion

A

1 centimetre = 10,000,000 nanometers

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13
Q

Eukaryotic Cell Organelle:

Cytoskeleton

A

• Cytoskeleton: Network of fibers which help organize the internal arrangement within cells. Three basic types of fibers compose cytoskeleton:

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14
Q

o Actin Filaments

A

 Thinnest fibers ~7nM

 Formed from protein

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15
Q

o Actin Microtubules

A

 Largest component of cytoskeleton ~25 nM

 Formed from protein Tubulin

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16
Q

o Intermediate filaments

A

 Intermediate in size and can vary

 Form from several proteins including vimentin & keratin

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17
Q

Prokaryotic Cells

A
  • Lack a true nucleus, Eukaryotic cells have a nucleus
  • Bacillus: Rod
  • Coccus: Spherical
  • Spirillum: Spiral
  • Vibro: Comma
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18
Q

Bacteria:

A

• Smallest organisms with a cellular structure
• 0.5 to 5 micrometre
• Occupy a variety of environments
• Vital to other organisms (decay and subsequent recycling of nutrients)
• Unicellular
• Some form filaments or chains, but are rare
• Antibiotics only work with particular types
• Resistant, bacteria that are completely resistance changed atmosphere
• Life comes from bacteria
Not bad because
• Would kill us if it disappeared
• Helps us function (ex. Digestion) vitamins, food
• Cause illness but only some do
Digests around the outside, live on the food, digest thing outside of body

19
Q

Energy is from

A

• Fermentation(hetero)
• Photosynthesis (purple chlorophyll)(Auto)
• Nitrogen fixation (waste, oxygen) (Chemo)
Chemotrophs: use very basic compounds, break or put together for energy

20
Q

Gram +

A
  • Thick murein (=peptidoglycan, made of protein and sugar)cell wall (polysaccharide)
  • No Lipopolysaccharide
  • No outer enzymes
  • Release enzymes and toxins
  • No plasmid loops of DNA
  • No pili
  • Surface proteins for recognition

• More simple
• Digest outside of cell
• Hydrolytic enzymes(
• Peptidoglycan (=murein) (protein and sugar)
• Very tough physically
• Toxins to kill
• White blood cell find it difficult to digest
(break down)
• Difficult to make vesicles, so make toxins and break it down outside and then getting it
• Enzymes put it outside digests you
• Neuroma and Lockjaw
• Gram test: black (b/c outside layer different)

21
Q

Gram -

A
  • Thin murein cell wall (polysaccharide)
  • Lipopolysaccharide layer for chemical protection
  • Enzymes on outer membrane
  • Does not release
  • Plasmid loops/rings of DNA
  • Often has pili, if not- slime (rare)
  • No surface proteins
  • More complex
  • Like to stick together to share information
  • Gram test: red
22
Q

Structure of Prokaryote

A
  • Internal membrane systems are scarce. Those present are involved in respiration, photosynthesis & nitrogen fixation.
  • No membrane bound organelles (such as mitochondria or chloroplasts).
  • Nucleoid region containing a loop of DNA lying free in the cytoplasm. Not associated with histone proteins (ie naked).
  • Naked DNA: no membrane around it
  • Plasmids: little loops of DNA, share info by this, esp. Surviving techniques
  • Capsule for sticking
  • Cell wall (often made of murein) - maintains cell shape and prevents cell from bursting.
  • Small, 70S ribosomes (eukaryotes = 80S).
23
Q

Structure of Prokaryote, sometimes present

A
  • Pili : Used for attachment to other cells or surfaces. Sex pili also used during conjugation. Little grappling hoops, tends to have these if no slime layer
  • Flagella for locomotion. Simple in structure and lacking microtubules. Spin rather than vibrate. Motor: 52 bits all necessary
  • Plasmid loops - small loops of DNA separate from the main loop.
  • Often contain genes for antibiotic resistance / toxin production.
  • Can be transferred from one bacterium to another during conjugation.
  • An outer slime capsule for additional protection.
  • Mesosome: infolding of the plasma membrane.
24
Q

Prokaryotic Reproduction:

A 
•	Binary Fission (asexual)
o	Cell copies DNA, split
o	Info doesn’t have to be identical
o	20 minutes to cycle
o	Evolution <- catch up with bacteria
o	Makes mistakes on purpose
•	Conjugation
o	Shares plasmids between each other
o	Don’t reproduce sexually
25
Q

Comparison: Eukaryotic

A
  • DINA linked with proteins (histones) Inside double membrane, linear structure (True Nucleus)
  • Organelles enclosed in membranes
  • Mitochondria
  • Pili absent
  • Flagella flex. Membrane bound
  • Ribosome 80s
  • Mitosis, meiosis
  • Animals, plants, fungi, protists
  • Does not always have cell wall
  • Plasma membrane on the outside of the cytoplasm
  • Mitochondria
26
Q

Comparison: Prokaryotic

A
  • DNA naked, circular, lose. No protein, can also have plasmids (lack nucleus)
  • NO specialised organelles with membranes
  • NO mitochondria
  • Pili present
  • Flagella solid and rotate
  • 70s ribosome
  • Binary fission, sex reproduction only occasional
  • Bacteria
  • Cell wall
  • Plasma membrane on the outside of the cytoplasm]
  • Much smaller
  • Pili, capsule, flagella
27
Q

Plant cell’s cell wall:

A
  • Fungal cell walls are made of chitin, while plant cell walls are made of the carbohydrate cellulose.
  • Consist of a primary cell wall made first and a woody secondary cell wall in some plants.
  • Helps keep cell shape, helps hold plant up against gravity and prevents excessive water uptake by osmosis.
28
Q

Animal cell’s gylcoproteins:

A
  • Used as a marker to identify cells (antigens).
  • Help stick specific cells together in tissues.
  • Recognition of certain molecules moving into the cell.
29
Q

Surface Area and Volume

A
  • Cell increase volume = make more heat by respiration, more waste and use more resources
  • Heat and materials are exchanged at cell surface
  • The SA:V ratio decreases, a cell finds it more difficult to exchange nutrients and resources as it gets larger. This limits cell size to about 200 micrometres
  • Diffusion is a limiting factor
  • Invagination
30
Q

Fluidity of the membrane

A
  • Lipids move laterally in a membrane
  • Unsaturated hydrocarbon tail of phospholipids has kinks that keep the molecules from packing together, enhancing membrane fluidity.
  • Cholesterol is hydrophobic & reduces membrane fluidity by reducing phospholipid movement at moderate temperatures but it also hinders solidification at low temperatures.
31
Q

Membrane Proteins

A

• Some have peripheral proteins are attached to the external & internal surface of the cell membrane.
• Integral proteins or transmembrane proteins are embedded & extend across the entire cell membrane. These are exposed to both the inside of the cell & the exterior environment.
o Some channel proteins have holes or pores through them so certain substances can cross the cell membrane. Channel proteins help move ions (charged particles) such as Na+, Ca+, & K+ across the cell membrane.
o Transmembrane proteins bind to a substance on one side of the membrane & carry it to the other side. e.g. glucose

32
Q

• Cell membrane proteins help

A

o move materials into & out of the cell
o change the density of the membrane
o recognition
o Chemical reactions.

33
Q

• Glycoproteins

A

help change the density/fluidity of the membrane- helping movement (pseudopodia) and support, aid sticking to other cells (adhesion) and cell recognition.

34
Q

Protein and function

A

Protein Function
Integral Hormone binding site
Immobilised enzymes
Protein pore Passive and facilitated transport
Carrier protein Active transport
Glycoprotein Cell and molecule recognition

35
Q

• Osmosis & diffusion

A

o Diffusion is the movement of particles (liquid or gas) from an area of high concentration to an area of low concentration
o Osmosis: the passive movement of water molecules, across a partially permeable membrane, from region of lower solute concentration to a region of higher solute concentration, diffusion of water molecules
o Simple diffusion: travelling directly through the membrane if they are small and generally uncharged, thus avoiding repulsion by the hydrophobic non-polar tails of phospholipids in the membrane

36
Q

• Passive & facilitated diffusion

A

o Faciliated diffusion: thorugh selective protein pores/transport proteins, if they match the shape and charge requirements to fit

37
Q

• Active transport

A

o Selective movement against the concentration gradient at protein pumps. Uses ATP from mitochondria
o Protein pumps: integral protein pumps embedded within membranes specific to molecule transported

38
Q

• Bulk transport using vesicles

A

o Solids and liquids by vesicles at membrane. Uses ATP from mitochondria
o Protein synthesis: rER produces proteins which travel through the lumen of the ER
o Transport in vesicles: Membranes produced by the rER flows in the form of transport vesicles to the Golgi, carrying proteins within the vesicles
o Modification: Golgi apparatus modifies proteins produced in rER
o Transport to membrane: Golgi pinches off vesicles that contain modified proteins and travel to plasma membrane
o Exocytosis: Vesicles then fuse with plasma membrane, releasing their contents

39
Q

Preparing for Mitosis

A

• Resting phase (G0):
o sometimes not thought as part of the cycle. Some cells rest here, others (damaged cells) may never proceed. These cells are not dividing.
• Interphase:
o G1-’growth’the cell is busily preparing for division- making many enzymes, organelles like mitochondria and chloroplasts, storing ATP and DNA fragments. This stage is very variable in length.
o S- ‘synthesis’ the DNA strands start to copy. Eventually each of the 46 DNA strands has an identical copy- making up a chromosome.
o G2- another gap stage where the cell is making proteins (usually microtubules) to help in the movement of DNA strands during mitosis. They check the chromosome copies. They make ATP. Often the cell will grow in size here.

40
Q

Mutation

A
  • Uncontrolled division during mitosis is called cancer and results in a mass of cells called a tumour. This can happen in any cell or tissue.
  • Due to DNA mutations, cancer cells ignore the chemical signals that start and stop the cell cycle.
  • DNA mutations disrupt the cell cycle.
41
Q

Mutations may be caused by:

A
  • Radiation
  • Smoking
  • Pollutants
  • chemicals
  • viruses
42
Q

Normal Cell Division

A
  • DNA is replicated properly.
  • Chemical signals start and stop the cell cycle.
  • Cells communicate with each other so they don’t become overcrowded.
43
Q

Cancer Cells

A
  • Mutations occur in the DNA when it is replicated.
  • Chemical signals that start and stop the cell cycle are ignored.
  • Cells do not communicate with each other and tumors form.

Biology (3 decks)

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