Cell Theory + Prokaryotes

A2.2.1 & A2.2.4-..9 & B2.2.1 & B2.2.3

cell theory (3)

1. all living organisms are made up of cells

2. all cells come from pre-existing cells

3. cells are the most basic unit of self-sustaining life

cellular structures found in all living organisms (3)

1. DNA as genetic material

2. cytoplasm composed of mainly water

3. plasma membrane composed of lipids

which type of ribosomes do prokaryotes have

70s

parts of a prokaryotic cell (6)

1. plasma membrane

2. cell wall

3. naked DNA (in a loop)

4. cytoplasm (w enzymes)

5. 70s ribosomes

6. nucleoid (region of cytoplasm where DNA is)

what are the 8 processes of unicellular organisms

1. Metabolism

2. nutrition

3. growth

4. excretion

5. homeostasis

6. movement

7. response

8. reproduction

parts of a eukaryotic cell

• plasma membrane

• cytoplasm

• nucleus

• 80s ribosome

• lysosome

• smooth endoplasmic reticulum (e.r.)

• rough e.r.

• golgi apparatus

• vesicles

• mitochondria

atypical cell in euks

• red blood cells

• phloem sieve tube elements

• skeletal muscle

• aspetate fungi

how is DNA in prokaryotes “naked”

unlike in euks, prokaryotic DNA is not necessarily tightly packed into chromosomes or histones

what are plastids

a family of double-membraned organelles

• found in plant cells (they have chloroplasts & amyloplasts)

centrioles

organelles composed of 9+2 arrangement of microtubules,

• used in animal cells to organise assembly of spindle of microtubules in mitosis/meiosis

cilia & flagella

microtubule structurs protruding from cell plasma membranes

• cillia ; moves fluid adjacent to cell (like hair)

• flagellum ; engage in beating action for cell movement (like a tail)

red blood cells (as atypical cell structure)

plasma membrane + haemoglobin (in cytoplasm)

• have no nuclei

• no mitochondria

• no ribosomes

skeletal muscle (as an atypical cell strucuture)

made of muscle fibers — each enclosed in a plasma membrane like a cell but quite long

• contain hundreds of nuclei

what cell structures are NOT organelles

• cell wall (bc outside of the cell’s membrane)

• cytoplasm (bc has diverse functions)

• cytoskeleton (bc extensive/not discrete structure extending cytoplasm)

advantages of cell compartmentalisation (euks)

• enzymes can function at optimum pHs

• substrates can be concentrated bc small volume

• prevents incompatable biological processes from mixing (ex. lysosomes would digest other cell parts if not separated)

metabolism

production of enzymes to catalyse chemical reactions in the cytoplasm

nutrition

the acquisition of energy and nutrients for growth and development

growth

increasing in size and dry mass using energy acquired from digested foods

excretion

metabolic waste products diffuse out of cell

homeostasis

regulation of internal conditions (ex. temperature)

reproduction

reproduces asexually (mitosis) or sexually (meiosis & gametes) — producing offspring