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Biology HL > Chapter 1 - Cell Biology > Flashcards

Chapter 1 - Cell Biology Flashcards

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1
Q

Example of unicellular organism: Chlamydomonas

A
  • Motile (moving), unicellular alga of fresh water habitats rich in ammonium ions.
  • 30um
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2
Q

Example of unicellular organism: Amoeba

A
  • Protozoan (eukaryote) of fresh water habitats

- 400um

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3
Q

Unicellular organism

A

Made of a single cell

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4
Q

Multicellular organism

A

Made of many cells

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5
Q

examples of multicellular organisms

A

Mammals & flowering plants

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6
Q

Essential functions of life in all organisms

A
  1. Nutrition
  2. Respiration
  3. Metabolism
  4. Excretion
  5. Reproduction
  6. Movement/locomotion
  7. Sensitivity
  8. Growth/development
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7
Q

What does the cell consist of?

A

-Nucleus surrounded by cytoplasm, contained within the cell membrane.

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8
Q

Nucleus

A

-Structure that controls and directs the activities of the cell.

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9
Q

Cytoplasm

A

-site of the chemical reactions of life (metabolism).

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10
Q

Plasma membrane

A

-Barrier controlling entry & exit from the cytoplasm.

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11
Q

Cell theory

A
  1. Cells are the building blocks of structure in living things.
  2. Cells are the smallest unit of life.
  3. Cells are derived from pre-existing cells by division.

+extra:

  1. Cells contain a blueprint (information) for their growth, development & behaviour.
  2. Cells are the site of all chemical reactions of life (metabolism).
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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)
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13
Q

Bacteria size range

A

0.5-10um

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14
Q

Cells of plants and animals size range

A

50-150um or larger.

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15
Q

Example of unicellular organism: Escherichia Coli

A
  • Bacterium found in intestines of animals e.g. humans

- 2.0um

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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.
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17
Q

Organelle

A

-A discrete structure within a cell, having a specific function.

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18
Q

Similarities between plant and animal cells

A
  • Cytoplasm
  • Nucleus
  • Plasma membrane
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19
Q

Vacuole

A

-Fluid filled space within cytoplasm, surrounded by a single membrane.

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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
Q

Magnification definition and formula

A

Number of times larger an image is than the specimen.

-Magnification = size of image/size of specimen

26
Q

Resolution definition

A
  • 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
Q

Surface area:volume ratios and cell size

A
  • 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
Q

Relationships between metabolism,cytoplasm, surface area and exchange of materials in a cell + summary

A
  • 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
Q

What are specialised cells in multicellular organisms organised into?

A

Tissues & organs

30
Q

Tissue definition

A

Group of similar cells that are specialised to preform a particular function e.g. heart muscle tissue of mammal.

31
Q

Organ definition

A

Collection of different tissues which preforms a specialised function e.g. heart of mammal.

32
Q

Gene definitions

A
  • 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
Q

Control of cell specialization

A
  • 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
Q

Cost of specialisation

A
  • 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
Q

Non-cellular organisation

A
  • 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
Q

Cell cycle definition

A

The time between one cell division and the next.

37
Q

How embryonic stem cell come about in the development of an organism and what happens next

A
  • 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
Q

Stem cell definition

A

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
Q

Differences between embryonic & adult stem cells

A

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
Q

What are the conditions needed for stem cells to be used in medical therapies (repair/replace damaged organs)?

A
  • 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
Q

Medical conditions that have been identified in which stem cell technologies may have the potential to bring relief or cure.

A
  • 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
Q

Stem cells = ethical implications

Where do stem cells come from?

A
  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
Q

Transmission electron microscopy (TEM)

A

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
Q

Scanning electron microscopy (SEM)

A

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
Q

Eukaryotic cells definition

A
  • Cells with a large, obvious nucleus with the surrounding cytoplasm containing many membranous organelles.
  • Plants, animals, fungi, protoctista.
46
Q

Prokaryotic cells definition

A
  • Cells that contain no true nucleus & cytoplasm doesn’t have the organelles of eukaryotes.
  • Bacteria
47
Q

Ultrastructure of the eukaryotic cell

A
  • 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
Q

Nucleus

A
  • 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
Q

Centrioles

A
  • 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.

Biology HL (1 decks)

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