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Bio L2 Cells
NCEA Level 2 Biology Life Processes at the Cellular Level AS 91156
| Term | Definition |
|---|---|
| active site | The part of an enzyme to which the substrate(s) bind. |
| active transport | The movement of a substance across a membrane against its concentration gradient, or in bulk. This requires energy. |
| aerobic respiration | Respiration occurring in the presence of oxygen. |
| anaerobic respiration | Respiration occurring in the absence of oxygen. |
| anaphase | The stage in cell division in which homologous chromosomes or sister chromatids separate by moving to opposite ends of the cell. |
| ATP | The form of energy used by all living things. |
| base pairing rule | A with T (adenine with thymine), and C with G (cytosine with guanine). |
| Calvin cycle | A series of reactions in the stroma of chloroplasts in which carbon dioxide is incorporated into glucose. Also called the light-independent phase or carbon fixation. |
| cell | The basic unit of life and the building block of all living things. |
| cell cycle | The series of events that take place in a cell, leading to its division. It includes interphase, mitosis (including prophase, metaphase, anaphase and telophase) and cytokinesis. |
| cell division | When a parent cell divides into two or more daughter cells. The two types are mitosis and meiosis. |
| cell membrane | A semi-permeable phospholipid bilayer forming the boundary of all cells, controlling the entry and exit of substances. |
| cell wall | Cellulose layer that surrounds plant cells (outside the cell membrane). |
| cellulose | Substance that plant cell walls are made of. |
| centromere | The point at which sister chromatids (two halves of a replicated chromosome) are joined together. |
| chlorophyll | A green pigment inside the chloroplasts of plants which captures light energy for photosynthesis. |
| chloroplast | Organelle which is the site of photosynthesis. Structure in plant cells which contains chlorophyll. |
| chromosome | Structure in the nucleus of cells which is made of DNA and protein and contains genetic information. |
| co-factor | Specific chemical which must be present for a particular enzyme to function. |
| concentration gradient | Difference in particle concentration between two regions. |
| cristae | Folds on the inner membrane of a mitochondrion. They increase the surface area for reactions to occur on, increasing the amount of ATP which can be produced during respiration. |
| cytoplasm | Jelly-like contents of the cell, located between the cell membrane and the nucleus. |
| denature | This will happen if the shape of an enzyme's active site is altered and the substrate(s) can no longer bind. This makes the enzyme inactive and can be caused by various agents, such as excess heat, or a change in pH. |
| diffusion | The movement of particles, through random motion, from an area of higher concentration to an area of lower concentration. |
| DNA | A double helix of linked nucleotides, carrying the genetic information of an organism. |
| DNA polymerase | An enzyme which builds a complementary strand of DNA during DNA replication, using free nucleotides inside the nucleus. |
| DNA replication | Process in which an exact copy of the DNA is made prior to cell division, so that there is a full set of genetic information available in each cell after cell division has occurred. |
| endocytosis | Active transport in which the cell membrane surrounds a substance and pinches off, enclosing it within a vesicle inside the cell. |
| endoplasmic reticulum | A network of flattened tube-like membranes throughout the cell. May have ribosomes attached. |
| enzyme | A biological catalyst that speeds up the rate of a reaction inside an organism. It is a type of protein and lowers the energy needed for a reaction to take place. |
| enzyme inhibitor | A substance that decreases an enzyme's activity by binding to the enzyme. |
| exocytosis | Active transport in which a membrane-bound vesicle inside the cell fuses with the cell membrane, releasing its contents outside the cell. |
| facilitated diffusion | Movement of substances from an area of higher concentration to an area of lower concentration across a cell membrane via special proteins called channel proteins or carrier proteins. Passive transport; does not require energy. |
| genome | All the DNA sequences of an organism. |
| glycolysis | The first stage of respiration, in which glucose is broken down into pyruvic acid. This stage occurs in the cytoplasm of cells and does not require oxygen. |
| Golgi bodies | System of folded membranes in the cell cytoplasm involved in producing and releasing secretions. |
| grana | Stacks of thylakoid discs found inside chloroplasts. |
| homologous chromosomes | A pair of similar-shaped chromosomes, each having genes for the same traits located at the same places. One chromosome of each pair is inherited from each parent. |
| induced fit model | Newer model for how enzymes work – the active site of the enzyme can temporarily change shape for the substrate(s) to bind to it and the reaction to occur. |
| ion pump | A protein in a cell membrane that moves ions across, against their concentration gradient (active transport; energy required). |
| lactic acid | Waste product of anaerobic respiration in the muscles; can cause muscle cramps. |
| lagging strand | This is the strand of DNA which must be made in short sections during DNA replication. |
| leading strand | This is the strand of DNA which is able to be made continuously during DNA replication. |
| light-dependent phase | The first phase of photosynthesis, in which water is split using light energy. Also called the light reaction or photolysis. |
| lock and key model | Old model for how enzymes work – the substrate can only fit into the enzyme if it is an exact match to the shape of the active site. |
| lysosome | Membrane-bound sac containing digestive enzymes. |
| matrix | The fluid-filled space enclosed by the inner membrane of mitochondria. It contains many enzymes which can function on the large surface area created by the cristae. |
| meiosis | A special type of cell division which results in the formation of sex cells (gametes). |
| metabolism | All the reactions occurring inside the cells of an organism. |
| metaphase | The stage in mitosis in which chromosomes line up in the middle of the cell. |
| mitochondrion | Organelle which is the site of respiration. |
| mitosis | A type of cell division leading to the formation of two daughter cells, each with an identical set of chromosomes. |
| nucleotide | Molecule consisting of a phosphate, a sugar and a nitrogenous base. |
| nucleus | Structure in cell containing the genetic information which controls the activity of the cell. |
| Okazaki fragments | The short sections of DNA made during DNA replication and joined together to form the lagging strand. |
| organ | A group of tissues with a particular function. |
| organelle | Various structures within the cytoplasm which have specific functions. Most are enclosed within their own membrane e.g. mitochondria, chloroplasts. |
| organism | Any individual living thing. |
| osmosis | The diffusion of water across a semi-permeable membrane. |
| passive transport | Movement of chemicals into or out of a cell without any energy cost to the cell (e.g. diffusion, osmosis). |
| photosynthesis | A process in plants in which carbon dioxide and water are converted into glucose (and oxygen) using light energy. |
| photosynthesis equation | CO2 + H2O + light energy -> C6H12O6 + O2 |
| photosynthesis word equation | Carbon dioxide + water + light energy -> glucose + oxygen |
| plasmolysis | Occurs in plant cells where the cell membrane pulls away from the cell wall as a result of water loss through osmosis. |
| protein | A molecule made up of amino acids and assembled at the ribosomes. |
| replicated chromosome | A chromosome which contains two (identical) sister chromatids. Forms as a result of DNA replication. |
| respiration | Process in which glucose is broken down to release energy in the form of ATP. |
| respiration equation | C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + energy (ATP) |
| respiration word equation | Glucose + oxygen -> carbon dioxide + water + energy (ATP) |
| ribosome | Small organelle which is the site of protein synthesis. Free in the cytoplasm and the ‘rough’ of rough endoplasmic reticulum. |
| RNA | Ribonucleic acid |
| semi-conservative | The term to describe that each DNA molecule contains one original strand and one newly-made complementary strand. |
| sister chromatids | The two (identical) halves of a replicated chromosome. Form as a result of DNA replication. |
| stomata | Tiny openings on a leaf surface which allow gases to be exchanged. |
| stroma | The fluid surrounding the grana inside a chloroplast. |
| substrate | The molecule(s) on which an enzyme acts. |
| surface area : volume ratio | For a given volume (size), cells need a large surface area across which substances (raw materials and waste products) can be transported. This is important for diffusion to be effective. |
| thylakoid | A flattened membrane disc inside a chloroplast; contains chlorophyll. |
| tissue | A group of cells of a similar type and function. |
| turgid | A plant cell which has built up pressure by taking up water by osmosis. |
| vacuole | Liquid-filled cavity within the cell cytoplasm. Large in mature plant cells. |
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