Topic 1- Key Concepts In Biology Flashcards
What do animal cells consist of?
It is a Eukaryotic cell meaning it has a nucleus.
Nucleus- contains genetic material
Cytoplasm- where most of the chemical reactions happen
Ribosomes- where proteins are made
Cell membrane- controls what goes in and out
Mitochondria- where most of the reactions for aerobic respiration take place
What do plant cells consist of?
Is a Eukaryotic cell
All of the ones in Animal Cells and also:
Cell wall- made of cellulose (strengthens the cell)
Chloroplasts- where photosynthesis occurs
Vacuole- contains cell sap, maintains the internal pressure of the cell
What do Bacterial cells consist of?
They are Prokaryotic cells meaning they have no nucleus
Cell membrane- controls what goes in and out
Ribosomes- where proteins are made
Chromosomal DNA- controls cells activities and replication
Flagellum- for movement
Plasmid DNA- can be passed between bacteria
What is Microscopy?
Electron microscopes were invented later than light microscopes.
They have higher magnification and resolution than light microscopes.
This means they let us see smaller things in more detail, so we can understand subcellular structures better now.
What are the three specialised cells?
Specialised cell- a cell that has a structure adapted to its function.
1. Egg cell- carries female DNA and feeds developing embryo
2. Sperm cell- transports male DNA to egg
3. Ciliated epithelial cell- moves substances along internal surfaces (E.g mucus in airways)
Cilia moves substances.
What do egg cells contain?
Nutrients in cytoplasm
Haploid nucleus- contains half the chromosomes of a normal body cell the sperm cell contains the other half
Cell membrane- changes structure after fertilisation to prevent more sperm entering
What do sperm cells contain?
Haploid nucleus-the other half of chromosomes
Tail for swimming to the egg
Lots of mitochondria- to provide energy for swimming
Acrosome- contains enzymes for digesting egg membrane
What are Enzymes?
Enzyme catalyse speed up chemical reactions
Each enzyme only catalyses one specific reaction because of the unique shape of its active site
Enzyme and substrate fit together like a lock and key
What are the factors affecting Enzyme Activity?
High temperatures and high and low pHs denature enzymes ( change the shape of the active site so the enzyme no longer works)
More substrate molecules mean enzyme and substrate are more likely to meet.
Enzymes in Organisms:
Enzymes break big molecules into smaller ones, which are used for life processes.
Enzymes also catalyse synthesis reactions- building big molecules from smaller ones.
Carbohydrates, (e.g starch) — carbohydrases —> sugars
Protein — proteases —> amino acids
Lipid — lipases —> glycerol and fatty acids
What is diffusion?
Diffusion- the net movement of particles from an area of higher concentration to an area of lower concentration.
Only very small molecules (E.g glucose) can diffuse across cell membranes.
What is Osmosis?
Osmosis- the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
What is Active Transport?
The movement of particles against a concentration gradient. It requires energy from respiration.
