Unit 1 Flashcards
Prokaryotic
Smaller, simpler cells e.g. bacteria
Eukaryotic
More complex e.g. plant and animal cells
Animal sub-cellular structures
Nucleus Cytoplasm Membrane Ribosomes Mitochondria
Plant sub-cellular structures
Nucleus Cytoplasm Membrane Mitochondria Ribosomes Cell wall Chloroplasts Vacuole
Nucleus
Contains genetic material that control the activity of the cell
Cytoplasm
A gel-like substance where most of the activities of the cell takes place
Mitochondria
Where most of the respiration reactions take place. Respiration transfers energy that the cell needs to work
Membrane
Holds the cell together and controls what goes in and out
Ribosomes
Ribosomes are involved in the translation of genetic material in the synthesis of proteins
Cell wall
Supports and strengthens the cell
Vacuole
It maintains the internal pressure to support the cell.
Chloroplasts
Where photosynthesis occurs
Chromosomal DNA
A long circular chromosome that controls the cell’s activities and replication
Plasmid DNA
Small loops of extra DNA that aren’t part of the chromosome. Plasmid DNA contains genes for drug resistance which can be passed between bacteria
Flagellum
A long, hair-like structure that rotates to move the bacterium. It can be used to make the bacteria swim away from harmful substances and move towards beneficial things like nutrients
Specialised cells
Specialised cells have a structure that makes them well adapted to their function.
Egg cell
Function: carry the female DNA
- contains nutrients in the cytoplasm to feed the embryo
- haploid nucleus
- Straight after fertilisation it’s Membrane changes shape to stop anymore sperm getting in. This makes the offspring end up with the correct number of DNA
Sperm cell
Function: transports the male DNA to the female’s egg.
- long tail so it can swim fast to the egg
- lots of mitochondria to provide energy from respiration to allow sperm swim
- haploid nucleus
- acrosome at the front of the head, where it stores enzymes needed to digest through the membrane of the egg cell
Ciliated epithelial cells
Epithelial cells line the surface of organs. Cilia is a hair-like substance on top of the surface of the cell.
Ciliated epithelial cells move substances- the cilia beat to move substances in one direction along the surface of the tissue.
For example, the lining of the airways contains lots of ciliated epithelial cells so it can move mucus up the throat and into the mouth where it can be swallowed and won’t reach the lungs.
Microscopes history
Light microscopes where invented in the 1590s. They work by passing light through a specimen to allow us to see things like nuclei and chloroplasts
Electron microscopes were invented in the 1930s and use electrons rather than light. They have a higher magnification and resolution to allow us to see smaller things in more detail like the internal structure of su-cellular structures. This gives us a better understanding on how cells work.
Magnification equations
Total magnification= eye piece lens magnification X objective lens magnification
OR
Magnification = image size/ actual size
Enzymes
Enzymes are biological catalysts. A catalyst is a substance which increases the speed of a reaction, without being changed or used up.
How do enzymes speed up reactions?
Every enzyme has an active site. This is where it joins onto a substrate to catalyse a reaction.
For the enzyme to work, the substrate has to fit into the active site. If the substrate doesn’t fit the enzyme’s active site the reaction can’t be catalysed.
Affect of temperature on enzymes
Changing the temperature changes the rate of an enzyme-catalysed reaction.
Increasing the temperature at first buy i gets too hot so some bonds holding the enzyme together break which changes the shape of the active site.
Affect of PH on enzymes
Ph affects enzymes. If it gets too high or too low, PH interferes with the bonds holding the enzyme together. This denatures the enzyme.
Most enzymes have an optimum PH of 7
Affect of substrate concentration on enzymes
The higher the substrate concentration, the faster the reaction as it is more likely the enzyme will meet up and react with a substrate. Up to a point, the active sites are full so adding more will make no difference
Ph and enzyme investigation controls
- The same volume of substrate and enzyme. (Different volumes can change the rate of reaction).
- Same concentration of enzyme and substrate.(same reason)
- Same temperature
Rate calculation
Rate = 1000/time
Rate in cm3s-1
Carbohydrases
Carbohydrases convert carbohydrates into simple sugars
Proteases
Proteases convert proteins into amino acids
Lipases
Lipases convert lipids into fatty acids and glycerol
Diffusion
Diffusion is the gradual movement of particles from an area of higher concentration to an area of lower concentration
Osmosis
Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to an area of lower water concentration
Heterotroph
Find own food
Autotroph
Make their own food
Saprotroph
Feed off dead matter
