Chapter 1 - Cell Biology Flashcards
(49 cards)
1
Q
Example of unicellular organism: Chlamydomonas
A
- Motile (moving), unicellular alga of fresh water habitats rich in ammonium ions.
- 30um
2
Q
Example of unicellular organism: Amoeba
A
- Protozoan (eukaryote) of fresh water habitats
- 400um
3
Q
Unicellular organism
A
Made of a single cell
4
Q
Multicellular organism
A
Made of many cells
5
Q
examples of multicellular organisms
A
Mammals & flowering plants
6
Q
Essential functions of life in all organisms
A
- Nutrition
- Respiration
- Metabolism
- Excretion
- Reproduction
- Movement/locomotion
- Sensitivity
- Growth/development
7
Q
What does the cell consist of?
A
-Nucleus surrounded by cytoplasm, contained within the cell membrane.
8
Q
Nucleus
A
-Structure that controls and directs the activities of the cell.
9
Q
Cytoplasm
A
-site of the chemical reactions of life (metabolism).
10
Q
Plasma membrane
A
-Barrier controlling entry & exit from the cytoplasm.
11
Q
Cell theory
A
- Cells are the building blocks of structure in living things.
- Cells are the smallest unit of life.
- Cells are derived from pre-existing cells by division.
+extra:
- Cells contain a blueprint (information) for their growth, development & behaviour.
- Cells are the site of all chemical reactions of life (metabolism).
12
Q
Cell size: units of length used in microscopy
A
- 1 metre (m) = 1000 millimetres (mm)
- 1 mm = 1000 micrometres (um)
- 1um = 1000 nanometres (nm)
13
Q
Bacteria size range
A
0.5-10um
14
Q
Cells of plants and animals size range
A
50-150um or larger.
15
Q
Example of unicellular organism: Escherichia Coli
A
- Bacterium found in intestines of animals e.g. humans
- 2.0um
16
Q
Louis Pasteur (1862) & his experiment:
A
- Established that life doesn’t spontaneously generate.
- Bacteria that “appears” in broth are microbes freely circulating in air, which contaminate exposed matter.
- Experiment= broth was sterilised, then either exposed to air or protected from air-borne spores in a swan-necked flask. Only broth in open flask became contaminated with bacteria.
17
Q
Organelle
A
-A discrete structure within a cell, having a specific function.
18
Q
Similarities between plant and animal cells
A
- Cytoplasm
- Nucleus
- Plasma membrane
19
Q
Vacuole
A
-Fluid filled space within cytoplasm, surrounded by a single membrane.
20
Q
Chloroplast
A
-Site where green plant cells manufacture food molecules by a process called photosynthesis.
21
Q
Centrosome
A
-Involved in nuclear division in animal cells.
22
Q
Differences between plant and animal cells table
A
- CELL WALL
Plant cells= cellulose cell wall present
Animal cell= no cellulose cell wall. - CHLOROPLASTS
Plant cell= many contain chloroplasts; site of photosynthesis
Animal cell= no chloroplasts; animal cells can’t photosynthesise. - PERMANENT VACUOLE
Plant cell= Large, fluid filled vacuole present
Animal cell= no large permanent vacuoles. - CENTROSOME
Plant cell= no centrosome
Animal cell= present outside nucleus - CARBOHYDRATE STORAGE PRODUCT
Plant cell= starch
Animal Cell= glycogen
23
Q
Paramecium
A
- Large protozoan (eukaryote) common in fresh water ponds.
- 600um
24
Q
Chlorella
A
- Small alga, abundant in freshwater ponds where its presence colours the water green.
- 20um
25
Magnification definition and formula
Number of times larger an image is than the specimen.
| -Magnification = size of image/size of specimen
26
Resolution definition
- Resolution of a microscope is its ability to separate small objects which are very close together.
- Resolution is determined by the wavelength of light.
- Light is composed of relatively long wavelengths, whereas shorter wavelengths give better resolution.
- Light microscope limit of resolution = 0.2um.
- Electron microscope resolution= 5nm
27
Surface area:volume ratios and cell size
- As the cell grows, the volume increases faster than the surface area.
- SA:V ratio falls.
- With the increasing size of a cell, less and less of cytoplasm has access to cell surface for exchange of gases, supply of nutrients & loss of waste products.
- Consequence= Cell cannot grow larger indefinitely, at certain size it stops and divides.
28
Relationships between metabolism,cytoplasm, surface area and exchange of materials in a cell + summary
- Rates at which materials can enter & leave a cell depend on the cell's surface area.
- Rates at which materials are used & waste products are produced depend on amount of cytoplasm within the cell.
- (Summary= rate of metabolism is a function of the cell's mass, rate of exchange of materials & heat energy that metabolism generates is a function of the cell's surface area.)
29
What are specialised cells in multicellular organisms organised into?
Tissues & organs
30
Tissue definition
Group of similar cells that are specialised to preform a particular function e.g. heart muscle tissue of mammal.
31
Organ definition
Collection of different tissues which preforms a specialised function e.g. heart of mammal.
32
Gene definitions
- Specific region of a chromosome which is capable of determining the development of a specific characteristic of an organism.
- Specific length of the DNA double helix (hundreds & thousands of base pairs long) which codes for a protein.
33
Control of cell specialization
- Nucleus of cell controls & directs the activities of cell.
- Information required for this exists in form of a nucleic acid, DNA.
- Nucleus contains DNA in thread-like chromosomes, which are linear sequences of genes.
- Genes control development of cell within the mature organism.
- When a cell is becoming specialised, its differentiating, some of its genes being expressed & activated.
34
Cost of specialisation
- Specialised cells are efficient at carrying out their function e.g. support, transport, protection.
- Resulting differences between cells = division of labour.
- Specialised cells are totally dependent on activities of other cells.
35
Non-cellular organisation
- There are multinucleate organs & organisms that aren't divided into separate cells = acellular organisation.
e. g. acellular organism - Rhizopus (pin mould), in which the plant body consist of fine structures called hyphae.
e. g. acellular organ - striped muscle fibres that make up skeletal muscles of mammals.
36
Cell cycle definition
The time between one cell division and the next.
37
How embryonic stem cell come about in the development of an organism and what happens next
- In development of new organism the first step is one of continual cell division to produce a tiny ball of cells.
- All these cells are capable of further division = embryonic stem cells.
- Next, most cells lose ability to divide as they develop into tissues & organs.
- However, few cells within these tissues retain the properties of embryonic stem cells and they're called adult stem cells.
38
Stem cell definition
Cell that has the capacity for repeated cell division while maintaining an undifferentiated state (self-renewal), and the capacity to differentiate into mature cell types (potency).
39
Differences between embryonic & adult stem cells
EMBRYONIC STEM (ES) CELLS:
-Undifferentiated cells capable of continual cell division & of developing into all cell type of an adult organism.
-Make up the bulk of embryo as it commences development.
ADULT STEM CELLS:
-Undifferentiated cells capable of cell divisions, these give rise to limited range of cells within a tissue e.g. blood stem cells give rise to red & white blood cells & platelets only.
-Occurring in growing & adult body, within most organs, replace dead or damaged cells e.g. in bone marrow, brain, liver.
40
What are the conditions needed for stem cells to be used in medical therapies (repair/replace damaged organs)?
- If stem cells can be isolated in large numbers & maintained in viable cell cultures.
- Isolated stem cells must be manipulated under reproducible conditions so that they:
- continue division in a sterile cell-culture environment.
- differentiate into specific, desired blood cell types.
- survive in a patient's body after they've been introduced.
- function correctly in the body for remainder of patient's life
- not trigger any harmful reactions within the tissues of the patient's body.
41
Medical conditions that have been identified in which stem cell technologies may have the potential to bring relief or cure.
- Stargardt's disease
- Parkinson's disease
- Cardiac muscle damage
- Type 1 diabetes - arises when beta-cells of the pancreas are destroyed by the body's immune system & severe lack of insulin results. Insulin (hormone) normally maintains the blood glucose concentration at about 90mg/100cm^3. In diabetics, level of blood glucose isn't controlled & becomes permanently raised.
42
Stem cells = ethical implications
| Where do stem cells come from?
1. ES cells may come from "spare" embryos produced by infertility clinics - today this remains controversial - objection= embryo's life destroyed in the process of gathering stem cells.
2. Blood extracted from umbilical cord at time of birth contains cells indistinguishable from ES cells. They're harvested & then multiplied by sterile cell-culture technique to yield sufficient ES cells for practical purposes.
3. Sources of adult stem cells identified in the brain, bone marrow, skin & liver. These are naturally activated by damage or disease in organ. Stem cells that generate blood cells are obtained from bone marrow and are already used in treatments.
43
Transmission electron microscopy (TEM)
Electron bean is passed through an extremely thin section of material.
Membranes & other structures are stained with heavy metal ions, making them electron-opaque do they stand out as dark areas in the image.
44
Scanning electron microscopy (SEM)
Narrow electron beam is scanned back and forth across the surface of specimen.
Electrons that are reflected or emitted from this surface are detected & converted into a 3 dimensional image.
45
Eukaryotic cells definition
- Cells with a large, obvious nucleus with the surrounding cytoplasm containing many membranous organelles.
- Plants, animals, fungi, protoctista.
46
Prokaryotic cells definition
- Cells that contain no true nucleus & cytoplasm doesn't have the organelles of eukaryotes.
- Bacteria
47
Ultrastructure of the eukaryotic cell
- In the living cell there's a fluid around the organelles - cytosol.
- Chemicals in the cytosol are substances formed & used in the chemical reactions of life - metabolism.
- The chemicals are known as metabolites.
- Cytosol & organelles are contained within the plasma membrane.
48
Nucleus
- Largest organelle in eukaryotic cell.
- 10-20um in diameter.
- Surrounded by a double-layered membrane - nuclear envelope.
- Contains chromosomes (thread-like structures visible at time of nuclear division, otherwise they appear as a diffuse network called chromatin)
- Nucleolus present in nucleus (tiny, rounded, darkly-staining body. Site where ribosomes are synthesised.)
- Most cells contain nucleus but exceptions - red blood cells.
49
Centrioles
- Tiny organelle consisting of 9 paired microtubules.
- In animal cells, 2 centrioles occur at right-angles outside nucleus, forming the centrosome.
- Before animal cell divides, centrioles replicate & their role is to grow spindle fibres - spindle is structure responsible for movement of chromosomes during nuclear division.
