Cells as the basis of life: Topic 1 Flashcards
fr3hyf (47 cards)
Describe the cell theory.
Everything is made of cells. Biogenesis, all cells come from other cells. The smallest organisational unit.
Distinguish between prokaryotic cells and eukaryotic cells.
Prokaryotic cells do not have a nucleus or organelles. Eukaryotic cells do.
Recite the basic cell inclusions.
Cell membrane
Cytoplasm
DNA
Ribosomes
What is the purpose of organelle membranes?
Allows enzymes and reactants to be concentrated in particular organelles of the cell. Maintains the right conditions for enzymes and reactants to function. Allows incompatible chemical reactions to take place simultaneously within the cell. Reduces the cell’s vulnerability to environmental changes.
What is the cell membrane?
Fluid structures composed of a
phospholipid bilayer, with associated protein, carbohydrate and cholesterol molecules. It seperates the extracellular fluid from the intracellular fluid. It regulates what moves in and out of the cell. It has receptors for intercellular communication.
Distinguish between hydrophilic and hydrophobic.
Hydrophilic is water loving. Hydrophobic is water hating.
Define lipophilic.
Loves fat.
Describe cholesterol.
Stabilizes the membrane without affecting the fluidity.
Describe proteins.
They are restricted in the cell membrane.
Integral protein - permanent
Peripheral protein - temporary
Transmembrane proteins go through the whole width of the membrane.
What do integral proteins do?
Transport channels for ions and molecules (enzymes). Are involved in signal transduction. Function incell-cell recognition. Connect cells to each other. Act as attachments to cytoskeleton and extracellular matrix.
Describe Carbohydrates.
Recognition and adhesion between cells, and in the
recognition of antibodies, hormones and viruses by cells.
Define permeablity.
Where molecules and fluids can flow through other cells and membranes. Selective permeability is where the cell or membrane decides what can come in and out.
Define Diffusion.
Movement of substances from a region of high concentration to a region of low concentration until dynamic equilibrium is reached.
Define osmosis.
The movement of water molecules from a region of high concentration to a region of low concentration through a semi-permeable membrane until dynamic equilibrium is reached.
What is a hypertonic solution?
Solution in which there is a higher concentration of solute particles/ lower
water concentration than the surrounding medium. Cell will take in water and become turgid (swollen).
What is an isotonic solution?
When the equilibrium is reached; the concentration in the solute is equal to the surrounding medium.
What is a hyptonic solution?
Solution in which there is a lower concentration of solute particles/ higher
water concentration than the surrounding medium. Cell will lose water and become flaccid (shrink).
Descibe facilitated diffusion.
When the molecule cannot diffuse on its own, it’ll need the help of a protein channel or carrier proteins.
Distinguish between passive and active transport.
Active transport is the net movement of dissolved substances into or out of cells through a concentration gradient. It requires energy. Passive transport does not use energy and uses osmosis, diffusion and faciliated diffusion.
Define concentration gradient.
The process of particles, which are sometimes called solutes, moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles.
Define bulk transport.
The movement of macromolecules such as proteins or polysaccharides into or out of the cell is called bulk transport. There are two types of bulk transport, exocytosis and endocytosis, and both require the expenditure of energy (ATP).
Describe organelles.
The compartments of a cell that perform specific functions. They are kept in cytosol (fluid) in the cell membrane. They only exist in eukaryotic cells.
Describe the nucleus.
Contains the DNA, kept in the chromosomes. The nucleolus responsible for the assembly of ribosomes.
Describe the ribosomes.
Made of proteins and RNA. Where protein synthesis is performed. They are either attached to the ER (endoplasmic reticulum) or roam free. They take mRNA and turn it into proteins.
