QUIZ 1 - INTRO TO CELL BIOLOGY

Who discovered and named the cell? In what year?

Robert Hooke in 1665

Who was the first man to observe a live cell?

Anton van Leeuwenhoek

What is the MODERN CELL THEORY? **

➢ All known living things are made up of cells.

➢ The cell is structural & functional unit of all living things.

➢ All cells come from pre-existing cells by division. (spontaneous generation does not occur).

➢ Cells contains hereditary information (nucleic acids) which is passed from cell to cell during cell division.

➢ All cells are basically the same in chemical composition.

➢ energy flow (metabolism & biochemistry) of life occurs within cells.

What is the smallest living mass called? What can it do?

• Protoplasm

• can live separately and able to divide to give a copy of itself

Cells differ by:

• shape

• size

• structure

• function

Cells have common features like:

• Colloidal nature

• Energy requirement (ATP)

• Nutrients supply

• Cellular association

• Life span

Ascending order of biological cells:

small molecule → virus → bacterium → animal cell → plant cell

4 elements that make up 96% of all living matter:

• carbon

• hydrogen

• oxygen

• nitrogen

Chemical composition of the cell:

• 70-90% water

4 groups of monomers - repeated building block, macromolecules

• sugars - polysaccharides

• fatty acids - lipids

• nucleotides - nucleic acid

• amino acids - proteins

Chemical composition of the body:

H2O - 85% (free & linked water)

Proteins - 10% ( structural & functional )

DNA - 0.4%

RNA - 0.7%

Lipids - 2%

Other organic compounds - 0.4%

Inorganic compounds - 1.5%

Proteins constitute most of the ___ ____ of a cell.

• dry mass

Prokaryotic cells:

Describes a cell possessing genetic material in the form of a single filament of DNA & not possessing a nucleus.

• found in bacteria & blue green algae.

Eukaryotic cells:

cell possessing genetic material carried on chromosomes, in a nucleus that is separated from the cytoplasm by nuclear membrane.

Development of eukaryotic cells FROM prokaryotic cells:

• eukaryotic cells engulfed smaller prokaryotes.

1. ancestral prokaryote

2. inward folding of cells membrane

3. cells with nucleus and internal membrane

4. a larger anaerobic cell engulfed smaller photosynthetic bacteria (endocytosis), formed symbiotic relationship.

5. engulfed photosynthetic bacteria become chloroplasts.

6. mitochondria evolves from engulfed aerobic bacterium.

Cell structure:

• cell membrane

• cytoplasm (cytosol and cytoplasmic organelles)

• nucleus (nuclear envelop, nucleoplasm, nucleolus & chromatin)

Animal cell organelles:

• centrioles **

• vesicles **

Plant cell organelles: **

• peroxisome **

• central vacuole **

• chloroplasts **

• cell wall **

Protoplasmic properties → responding & interacting with the environment

irritability: ability of the cell to respond to a stimulus - expression of life itself

contractility: changes shape/length to achieve locomotion

conductivity: some cells transmit a wave of excitation from one site to another. (ex. 1st and 2nd defense in immune cells)

absorption: get in substances from the environment

Protoplasmic properties → energy & waste

respiration: oxygen interacts with nutrients to produce energy (ATP molecules), CO2, water, plus waste

fermentation: breaks down glucose without oxygen

secretion: a cell releases useful material externally

excretion: elimination of waste products from the cell

Protoplasmic properties → cell activity & continuation

movement: internal movement of protoplasmic components; cilia, flagella and leukocytes.

growth: increase in cell size due to increasing the amount of protoplasm.

reproduction → achieved by cell division either by mitosis or meiosis.