Cell Theory

Front 1

Outline the cell theory.

Back 1

- Cells are the smallest part of a living organism
- Cells are the building blocks of the structures of living organisms,
- Cells are derived from pre-existing cells by cell division.

Front 2

What happens to the surface area: volume ratio as cells get bigger?

Back 2

The ratio decreases. The volume of the cell increases faster that the surface area. As the cell increases in size, less and less of the cytoplasm has access to the cell surface to exchange gases, nutrients and waste.

Front 3

What are the advantages of using adult stem cells?

Back 3

- No embryo needs to be killed
- cells are fully compatible when used in the same person
- Less chance of tumours developing in comparison to embryonic stem cells

Front 4

Name the structures of a prokaryotic cell. What is an example of a prokaryotic cell?

Back 4

- pili (enable atachment to surfaces and other bacteria)
- 70s ribosomes
- nucleiod (naked and circular)
- cytoplasm
- plasma membrane
- thick cell wall
- flagella (for movement)
e.g E. Coli

Front 5

Compare the features of a prokaryote and a eukaryote.

Back 5

Prokaryotes: no mitochondria present, large permanent vacuole present, 70s ribosomes, cell wall present, circular strand of naked DNA in the cytoplasm, very few organelles
Eukaryotes: mitochondria present, small, temporary vacuole, 80s ribosomes, DNA organised in double helix and encased in a nuclear envelope, organelles bound by membranes that compartmentalise functions

Front 6

What are the structures and functions of a eukaryote?

Back 6

Plasma membrane; a barrier that controls what enters and exists the cell, cytoplasm; the site of metabolic reactions, 80s ribosomes; site of protein synthesis, mitochondria; site of aerobic respiration, lysosome; contains digestive enzymes which breakdown unwanted chemicals, toxins and organelles, rER; modifies proteins made by the surrounding ribosomes for export, golgi apparatus; further modifies proteins for export and nucleus; contains the genetic material which controls cell activity.

Front 7

What are the differences between plant and animal cells?

Back 7

Plant cells have: chloroplasts, cell walls and large permanent vacuoles
Animals cells do not have chloroplasts or cell walls but can have small, temporary vacuoles

Front 8

What function does the plant cell wall serve?

Back 8

- It maintains cell shape
- prevents excessive water uptake
- holds the plant upright against the force of gravity

Front 9

Explain the hydrophobic and the hydrophilic properties of the plasma membrane.

Back 9

There is always a water solution on either side of the plasma membrane. The phosphate heads are hydrophilic because of the hydrogen bonds they form with water solutions. The fatty acid tails are hydrophobic and want to remain in contact with each other to avoid water thus creating a bilayer.

Front 10

Define diffusion

Back 10

Diffusion is the movement of particles from an area of high concentration to an area of low concentration

Front 11

Define osmosis

Back 11

Osmosis is the movement of water molecules from an area of high solute concentration to an area of low solute concentration across a partially permeable membrane.

Front 12

Explain active transport

Back 12

Active transport is the movement of particles/molecules from an area of low concentration to an area of high concentration (against the concentration gradient) thus it requires ATP.
1) specific molecules enter the plasma membrane of the carrier protein.
2) The membrane hydrolyses ATP to from ADP+Pi (releases energy)
3) The energy released from hydrolysis causes a change in shape of the carrier protein allowing the molecule to move from one side of the membrane to the other

Front 13

What are the two types of bulk transport?

Back 13

Exocytosis ( vesicle membrane fuses with the plasma membrane to export components out of the cell)
Endocytosis (a vesicle is formed by the infolding of the plasma membrane - the vesicle buds off)

Front 14

What are the four stages if cell division?

Back 14

Prophase - supercoiling of chromosomes, nuclear envelope disappears, spindle microtubule starts to form
Metaphase - chromosomes align at the equator of the cell, the microtubule network is complete and attach to the centromeres of the chromosomes
Anaphase - centromeres split, the sister chromatids are separated and pulled to the opposite sides of the cell
Telophase - chromosomes uncoil, nuclear envelope reforms, microtubules breakdown

Front 15

What activities involve mitosis?

Back 15

Growth
Tissue repair
Embryonic growth and
Asexual reproduction