Biology Flashcards
Nucleus
Controls cell activity
Cytoplasm
Site of chemical reaction
Cell membrane
Control which substances leave and enter the cell
Mitochondria
Aerobic respiration
Ribosomes
Protein synthesis
Cell wall
Gives the cell support - made of glucose
Vacuole
Contains cell sap
Chloroplast
The site of photosynthesis- glucose is produced
What are plant cells made of
Cellulose
What are cells
The building blocks of all living organisms
Name the four types of cells
Animal , plant , fungal and bacterial
What are plasmids
Small pieces of DNA that allow genetic materials to be transferred from one bacterial cell to another
What is circular DNA
Floats around in the cytoplasm
What cell does not have a nucleus
Bacterial
How many chromosomes does each human cell have
46
What kind of cells result from uncontrolled cell division
Cancer cells
What are stem cells
Unspecialised cells that have the ability to divide to self renew
What are the three characteristics of a stem cell
- The ability to self renew
2. The ability to develop into new specialised cells
What are the three characteristics of a stem cell
- The ability to self renew
- The ability to develop into new specialised cells
- There long life span
What are embryonic stem cells
Cells that can develop into any type of cells
What does the cell membrane contain
Protein and phospholipid molecules
Where are the protein molecules found
Embedded in the two layers of phospholipids
What is the cell membrane described as
Selectively permeable
What does selectively permeable mean
Only lets some substances through but not others
Name three substances that can pass through the membrane
Water , oxygen , glucose , amino acids or carbon dioxide
What are the two substances that cannot pass through the membrane
Starch and protein
How do carbon dioxide and water leave the cell
Via the cell membrane
Name the two types of passive transport
Diffusion and osmosis
Describe passive transport
It occurs down a concentration gradient and does not require energy
Describe the process of diffusion
Diffusion is the movement of molecules down a concentration gradient from a higher to a lower concentration
If the concentration of sugar was 75% what would be the concentration of water
25%
If the concentration of salt was 27% what would be the concentration of water
73%
Describe the process of osmosis
Osmosis is the movement of water molecules down a concentration gradient from a higher to a lower water concentration
What are the steps of percentage change
- Work out the difference between the two numbers
- Divide the difference by the original number
- Multiply by 100
Does active transport require energy
No
Describe active transport
Active transport requires energy for the membrane proteins to move molecules and ions AGAINST the concentration gradient
What way does active transport move
Lower to higher
What happens if animal cells are immersed in concentrated salt solution
The cell becomes shrivelled
What happens if an animal cell is immersed in water
The cells swell and eventually burst
What happens if an animal cell is immersed in water
The cells swell and eventually burst
Why is cell division essential
To allow organisms to grow and repair
What happens during cell division
The parent cell divides to produce two identical daughter cells
Describe the 1st and 2nd step in mitosis
- Long uncoiled chromosomes in the nucleus replicate
2. Chromosomes shorten and thicken
Describe the 3rd and 4th step of mitosis
- Chromosomes line up along the equator of the cell
4. Pairs of chromosomes are pulled apart
Describe the 5th and 6th step of mitosis
- Nuclear membrane reforms
6. The cytoplasm divides and two identical daughter cells form
How to you calculate cell size
Field of view (FOV) divided by the number of cells
