CELL BIOLOGY: 1.1 introduction to cells Flashcards
1
Q
Cell Theory
A
- All organisms are made up of cells
- The cell is the smallest unit of life
- Cells only arise from pre-existing cells
2
Q
Striated muscle fibres
A
- Muscle cells fuse to form fibres that may be very long (>300mm)
- Multinucleated fibres surrounded by a single, continuous plasma membrane
- Challenges the idea that cells always function as autonomous units
3
Q
Aseptate fungal hyphae
A
- Have filamentous structures called hyphae, which are separated into cells by internal walls called septa
- Some fungi does not have cellular partitions and therefore has continuous cytoplasm along the hyphae
4
Q
Unicellular Organisms
A
- Smallest organism capable of independent life
- Single cell that can carry all 7 life functions
5
Q
Paramecium (heterotroph):
A
- Unicellular protozoa (eukaryotes)
- Usually less than 0,25mm in size
- Widespread in aquatic environments, specially in stagnant ponds (less oxygen)
- Heterotrophs: feed on food participles they find in their environment
-Challenges the idea that living structures are composed of discrete cells, that cell is a single unit
6
Q
Giant Algae
A
- Large in size (eg: Acetabularia may exceed 7 cm in length)
- Challenges the idea that larger organisms are always made of many microscopic cells
7
Q
Functions of Life: Mr. SHENG
A
- Metabolism: living things undertake essential chemical reactions
- Reproduction: living things produce offspring either sexually or asexually
- Sensitivity: living things are responsive to internal and external stimuli
- Homeostasis: living things maintain a stable internal environment
- Excretion: living things exhibit the removal of waste products
- Nutrition: living things exchange materials and gasses with the environment
8
Q
SA:Vol Ratio
A
- The rate of metabolism of a cell is a function of its mass/volume
- Larger cells → more energy for sustaining essential functions
9
Q
Surface area
A
- Determined by cell membrane
- Cell membrane regulates what goes in and out of the cell
- Large surface area → more exchange
10
Q
Volume
A
- Determined by cytoplasm
- Most metabolic reactions take place in the cytoplasm
- Metabolic reactions require gases and chemical nutrients and produces waste products
11
Q
SA vs Vol:
A
- The larger the cell → the larger the cell membrane + volume
- However volume increases more rapidly than surface area therefore decreasing SA:Vol
- If metabolic rate > rate of exchange → low SA:Vol → cell die
12
Q
Who has a larger and a smaller SA:VOL ratio
A
- Small cells have a larger surface area → Molecules have a shorter distance to diffuse within the cell → more effective
- Large cells have smaller surface area → Within the cell molecules have a larger distance to diffuse → less effective
13
Q
Magnification
A
For drawing microscopic structures:
- A title including the identity specimen: name of organism, tissue or cell
- Magnification or scale should be included to indicate relative size
- Identifiable structures should be labelled
14
Q
Emergent properties
A
- Multicellular can complete functions that unicellular organism cannot
- The collective action of individuals cells combined creates new synergistic effects
15
Q
Differentiation
A
- Process during development where newly formed cells become more specialised and distinct from one another as they mature
- All cells of an organism share an identical genome
- But the activation of certain genes within a given cell by chemical signals causes differentiation
18
Q
Types of Stem cells
A
19
Q
Stem Cells Therapy
A
Stem cells are self-renewal so they can replace damaged or diseased cells with healthy, functioning ones
