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Biology: Cells mid-unit test (Cells (Definitions (Mitochondria: Site of…
Biology: Cells mid-unit test
Cells
Plant cells
Cell wall
Nucleus
Mitochondria
Ribosomes
Cell membrane
Cytoplasm
Chloroplasts
Vacuole
Animal cells
Cell membrane
Ribosomes
Cytoplasm
Mitochondria
Nucleus
Bacterial cells
Flagellum
Cell wall
Cell membrane
Circular chromosome
Plasmid
Cytoplasm
Ribosomes
Capsule
Fungal cells
Cell wall
Cell membrane
Vacuole
Nucleus
Mitochondria
Cytoplasm
Ribosomes
Definitions
Mitochondria: Site of ATP production in aerobic respiration
Plasmid: Small ring of DNA found in bacterial cells
Cytoplasm: Site of various chemical reactions
Ribosomes: Site of protein synthesis
Nucleus: Controls the cells activities
Chloroplast: Uses light energy to make plant food through a process known as photosynthesis
Vacuole: Helps to support the cells & contains a solution of water, sugars, and salts
Cell membrane: Controls what enters and exits the cell
Cell wall: Rigid structure helping to support the cell, outer layer of the cell
Transport across cell membranes
Cell membrane
The cell membrane is made up of...
Phospholipids
Phosphates
Fatty acid tails
Proteins
Selectively permeable: Only lets in certain substances
Diffusion
Different concentrations of substances exist between cells and their environment
Diffusion does NOT require energy as it is passive transport
Passive transport occurs down a concentration gradient
Examples of passive transport
Diffusion
Osmosis
Diffusion: The movement of molecules down a concentration gradient from a higher to a lower concentration
Substances which are examples of diffusion
Glucose: Diffuses from outside the cell to inside the cell
Carbon dioxide: Diffuses from inside the cell to outside the cell
Oxygen: Diffuses from outside the cell to inside the cell
Osmosis
The movement of water particles from a high water concentration to a low water concentration
Animal Cells
Burst if in pure water
Shrink if in a high sucrose solution
Plant cells
If in distilled water they may become turgid
If in a high sucrose solution become plasmolysed
Active transport
Requires energy for membrane proteins to move molecules and ions against the concentration gradient
Cell walls
Plant cell: Cell wall made of cellulose
Animal cell: No cell wall
Fungal cell: Different materials and structure to plant and bacterial cell walls
Bacterial cell: Different materials and structure to plant & fungal cell walls
DNA and Proteins
DNA
Double stranded helix held by complementary base pairs
Carries the genetic information to make proteins
Four different bases
Cytosine
Adenine
Guamine
Thymine
A & T are always paired together
C & G are always paired together
The sequence of bases along a strand is the genetic code
This determines the amino acid sequence in proteins
A gene is a sequence of DNA which codes for a protein
Proteins
mRNA
Messenger RNA
Messenger RNA is a molecule that carries a complementary copy of the genetic code from the DNA , in the nucleus, to a ribosome where the protein is assembled from amino acids
Proteins is made up of a sequence of amino acids