Cells

Protist

A group of unicellular organisms that are either autotrophic e.g. Euglena or heterotropic e.g. Paramecium. Possess a nucleus and other membrane-bound organelles.

Nuclear Membrane

A double-layered membrane that surrounds the genetic material. Nuclear pores allow material to move in and out of the nucleus.

Nucleus

A large round membrane bound organelle that surrounds the genetic material. To control the activities in the cell.

Flagellum

A long projection from the cell membrane. Used to move unicellular organisms.

Sap Vacuole

A membrane bound region within the cytoplasm of a plant cell. Contains cell sap (water and other materials e.g. salts, sugars, ions). Storage of materials, removal of toxic products and the site of pigment deposition. The storage of water results in the development of turgor pressure.

Vesicle

A membrane bound sphere. Involved in storage or transport.

Oral Groove

A permanent ciliated channel found on one side of heterotrophic unicellular organisms e.g. Paramecium Directs food particles down the channel to where a food vacuole will form.

Golgi Apparatus

A stack of membrane bound vesicles. Involved in packaging, storing, modifying and secreting chemicals within and out of the cell.

Paramecium

A unicellular organism that lives in freshwater, uses contractile vacuoles and mitochondria to actively get rid of excess water, is covered in cilia which it uses to move and to direct food into its oral groove.

ATP

Adenosine tri-phosphate: The form of chemical energy made in respiration from the breakdown of glucose with oxygen.

Factor: Oxygen

Aerobic Respiration - Oxygen. Lack of oxygen: reduce the amount of ATP energy released into the cell by mitochondria. Thus, lack of ATP available for other processes: Lower metabolic rate.

Unicellular Organism

An organism that consists of one cell only; may be prokaryotic e.g. Bacteria or a protist eukaryote e.g. Paramecium or Euglena.

Mitochondrion

An oval-shaped organelle made up of two membranes, inner and outer, cristae and matrix. The site of respiration.

Cell Membrane

Cell organelle found in all cells which is made up mainly of a lipid bi-layer and proteins. Controls the entry of chemicals in and out of the cell and cell recognition.

Cell Wall

Cellulose structure found outside of cell membrane in plant cells. Provides strength and support to the plant cell.

Factor: Enzymes

Enzymes denatured by high temps >45degC. Globular proteins in the cell membrane denature - becomme leaky: No longer able to osmoregulare the movement of materials in/out of cell. Increase in temp - reactants moving faster: more successful collisions therefore increase in rate of reaction. High temps >45degC: rate of these reactions will decrease/stop as enzymes denatured. Some bacteria (thermophiles) are adapted to be able to survive in high temps: Do not denature.

Centriole

In all animal cells and most unicellular organisms. Two tiny rod-shaped structures at right angles to each other outside the nucleus. Move in cell division to opposite poles where the produce the spindle which then moves the chromosomes apart.

Genetic Material

In the nucleus of most plant and animal cells. Carries the genetic code for the synthesis of two chromatids joined by a centromere.

Cristae

Infolding/projections of the inner membrane of the mitochondria. To increase the surface area for the process of respiration.

Cytoplasm

Jelly-like fluid found inside the cell membrane. Where many chemical reactions of the cell take place.

DNA

Main chemical component of the chromosome (genetic material).

Lysosome

Membrane bound organelle which contains digestive enzymes. Involved in the breakdown of worn out organelles and digestion of other materials.

Ribosome

Organelle found in all living organisms, either free floating or attached to the ER. The site of protein synthesis in which amino acids are joined together.

Chloroplast

Organelle found in photosynthetic plant cells and in autotrophic protists. Made up of a double membrane, stroma and grana. The site of photosynthesis.

Rough ER

Organelle found in plant and animal cells with ribosomes scattered over the surface. Involved in the production, folding and packaging of proteins made by the ribosomes.

Smooth ER

Organelle found in plant and animal cells. Involved in the production, of lipids, steroids and membranes.

Plasma Membrane

Organelle found outside the cytoplasm in all living cells. It is made up of a lipid bi-layer with proteins found on the surface and penetrating the layer, carbohydrates and cholesterol. It acts as a boundary, controls the entry and exit of material in and out of the cell, as well as bring involved in cell recognition.

Grana

Piles of flattened sacs within the chloroplasts which contain the chlorophyll. For absorbing light energy in light phase of process.

Factor: Water

Plant cells - Flaccid: Cell has too little water to maintain cell turgor. Guard cells lose water and close - stop further loss of water. Plant will wilt. Chemical reactions take place in water. Photosynthesis requires water - lack: reduce amount of glucose produced. Transpiration will cease - guard cells close: plant could overheat. Uptake of mineral is hampered in limited water.

Cell Respiration

Process occurring in the mitochondria of cells which breaks down glucose in the presence of oxygen to release energy in the form of ATP.

Secretion

Process whereby a cell releases chemicals out of the cell; Golgi Bodies are involved in packaging chemicals for secretion or release out of the cell.

Cilia

Projections from the cell membrane of some unicellular organisms, plant and animal cells. Movement of chemicals over the cell. Movement of the cell.

Factor: Nutrients

Red blood cells require the mineral iron to combine with haemoglobin to be able to transport oxygen around an organism. Lack - anaemia. Chlorophyll contains Magnesium. Lack - Decrease in photosynthetic rate.

Turgor

The state of a plant cell when it has taken in a maximum amount of water.

Double Helix

The structural form of the DNA.

Lamellae (thylakoids)

Sheet-like membranes that are found within the chloroplast. To hold the chlorophyll molecules in such a position as to receive the maximum amount of light.

Eye Spot

Small orange, light sensitive granule (carotenoids) found in some photosynthetic unicellular organisms. To maximise photosynthesis by being able to detect areas of higher light intensity.

Vacuole

Small, fluid-filled sac in animal cells. Temporary storage.

Anal Pore

Specialised region of the cell surface where food vacuoles attach and rupture to the outside (most unicellular protists e.g. Paramecium). Removal of wastes from digestion out of the cell.

Organelles

Structures found within the cytoplasm of the cell that perform a specific function; most are membrane bound.

Factors that Affect Cell Structures and Processes

Temperature. Oxygen. Water. Nutrients.

Cellulose

The chemical component of the cell wall made of insoluble carbohydrate fibres.

Nucleolus

The densely staining region of the nucleus. Makes RNA, a chemical used to form the ribosomes.

Matrix

The fluid part of the mitochondria. Where the second stage of respiration occurs.

Stroma

The liquid part of the chloroplast. Where the dark phase of photosynthesis takes place.

Osmoregulation

The process of maintaining a constant water concentration within a cell. Unicellular organisms that live in freshwater use contractile vacuoles to get rid of excess water that has entered.

Photosynthesis

The process that occurs in the chloroplast of plants and autotrophic unicellular organisms e.g. Euglena, where light energy is used to combine CO2 and H2O to form glucose and oxygen is given off as a waste product.

Lipid Bilayer

Two layers of lipids that form the plasma membrane. The lipids are orientated with the heads of the lipid molecules facing out.

Eukaryotic Cells e.g. Paramecium, Amoeba, Euglena, Yeast, Plants, Animals, Mushroom

Uni/Multicellular. Genetic material enclosed wihtin nucleus by nucleus membrane. Linear DNA wound around histone. Cell membrane. May possess cell wall. Ribosomes + additional organelles. May posses flagella. Greater degree of organisation - increase in cell size.

Euglena

Unicellular autotrophic organism, has chloroplasts and a flagella for movement. Eyespot to detect light which it moves to using its flagella to maximise photosynthesis.

Amoeba

Unicellular organism (heterotrophic) that possesses a contractile vacuole if living in freshwater.

Prokaryotic Cells e.g. Bacteria, Blue-Green Algae

Unicellular. Genetic material floats freely in cytoplasm - no nucleus. One circular chromosome. DNA - not wound around histone. Rigid cell wall. Cell membrane. Non-membrane bound ribosomes floating freely - production of proteins. May possess flagella - Beat: Move cell along.