As Biology Unit 1 Module 1

Front 1

Structure inside a cell. Each has a specific function and many are surrounded by membrane.

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Organelle

Front 2

A polymer consisting of many amino acid monomers covalently bonded together.

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Protein

Front 3

A molecule used to store energy temporarily in organisms. The molecule is broken down to release energy to drive metabolic processes.

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ATP

Front 4

Pigments found in chloroplasts of plant (and some protoctist) cells. Each molecule consists of a hydrocarbon tail and a porphyrin ring head with a magnesium atom.

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Chlorophyll

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A protein molecule that acts as a biological catalyst.

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Enzyme

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Cells that have a nucleus inside a nuclear envelope, and other membrane-bound organelles.

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Eukaryotic cell

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Chemicals made in endocrine glands that are carried in the blood to target cells/tissues/organs. They act as chemical messengers.

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Hormone

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Process by which plants, some bacteria and some protoctists make food using carbon dioxide, water and sunlight energy.

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Photosynthesis

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Also known as the plasma membrane.

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Cell surface membrane

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An organelle found in plants, which contains chlorophyll and is responsible for photosynthetic activity in the plant.

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Chloroplast

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A linear DNA molecule wrapped around histone proteins found in the nucleus. Become visible in prophase of cell division.

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Chromosome

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A polymer of nucleotide molecules that form the instructions for the synthesis of proteins found within organisms. Contains the 5-carbon sugar deoxyribose.

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DNA

Front 13

A 6-carbon monosaccharide sugar. Very important source of energy within cells. Substrate for glycolysis.

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Glucose

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Membrane-bound organelle in eukaryote cells. Involved in the modification and transport of proteins.

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Golgi apparatus

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Membrane-bound vesicles made by pinching off from the Golgi body. They usually contain digestive enzymes.

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Lysosome

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All the chemical reactions that take place in an organism.

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Metabolism

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The organelle found in cells in which most of the ATP synthesis occurs. It is the site of aerobic respiration.

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Mitochondrion

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A large, membrane-bound organelle found in eukaryotic cells, which contains the genetic material in the form of chromosomes.

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Nucleus

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The process in which energy is released from complex molecules, such as glucose, within cells and transferred to molecules of ATP.

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Respiration

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The organelle on which proteins are synthesised inside the cell.

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Ribosome

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A group of similar cells that perform a particular function.

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Tissue

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Describes a cell that is full of water as a result of entry of water due to osmosis such that pressure of the cell wall prevents more water entering.

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Turgid

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Movement of substances across membranes against their concentration gradient, requiring the use of energy in the form of ATP.

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Active transport

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An organic compound that contains both an amino group(–NH2) and a carboxyl group (–COOH). The monomers of protein molecules.

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Amino acid

Front 25

Method of cell division in bacteria. The DNA replicates and the cell divides into two, each having the same DNA as the parent cell.

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Binary fission

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A protein found in membranes, which is capable of carrying a specific molecule or ion through the membrane by active transport.

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Carrier protein

Front 27

A protein pore that spans a membrane, through which small ions and water soluble molecules may pass.

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Channel protein

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Material staining dark red in the nucleus during interphase. It consists of nucleic acids and proteins. Condenses into chromosomes during prophase of nucler division.

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Chromatin

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Short extensions of eukaryotic cells, typically 2–10 µm long and 0.03 µm in diameter. Used for locomotion or to move fluids or mucus over a surface.

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Cilia

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The folds found in the inner membrane of a mitochondrion. Stalked particles containing ATP synthase are found here.

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Cristae

Front 31

The development and changes seen in cells as they mature to form specialised cells.

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Differentiation

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The net movement of molecules or ions in a gas or liquid from an area of high concentration to an area where they are less concentrated.

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Diffusion

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Any system where different parts perform specialised functions, each contributing to the functioning of the whole, display this attribute.

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Division of labour

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A series of membrane-bound, flattened sacs extending from the outer nuclear membrane through the cytoplasm. Comes in rough and smooth forms.

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Endoplasmic reticulum

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An organism having cells with a nucleus and membrane-bound organelles.

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Eukaryote

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Sex cells, usually haploid (one set of chromosomes). Fuse during sexual reproduction to form zygotes (diploid).

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Gamete

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A length of DNA that carries the code for the synthesis of one (or more) specific polypeptide(s).

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Gene

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A protein with carbohydrate molecules attached.

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Glycoprotein

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Type of protein associated with DNA in eukaryotes. DNA is wound around them to form chromatin.

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Histone

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Associating with water molecules easily (water-loving).

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Hydrophilic

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Water-repelling (water-hating).

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Hydrophobic

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Energy of movement.

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Kinetic energy

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Undifferentiated plant cells capable of rapid cell division.

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Meristem

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Nuclear division that results in the formation of cells that are genetically identical to the parent cell.

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Mitosis

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The movement of water molecules from a region of higher water potential to a region of lower water potential across a partially permeable membrane.

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Osmosis

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A membrane that will allow some molecules to pass through but will not allow some others to pass through.

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Partially permeable membrane

Front 47

The membrane that surrounds every cell, forming the selectively permeable boundary between the cell and its environment.

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Plasma membrane

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Small, circular piece of DNA present in some bacterial cells. May have genes for antibiotic resistance and can also be used as vectors in genetic engineering.

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Plasmid

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Detachment of the plasma membrane from the cell wall as the cytoplasm shrinks when water is lost from a plant cell.

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Plasmolysis

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An organism with cells that do not contain a true nucleus.

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Prokaryote

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Protein or glycoprotein molecules on cell surfaces, used for attachment of specific substances such as hormones. Can be exploited by viruses.

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Receptor site

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Cells in the epithelium of roots that have long extensions to increase surface area for the absorption of water and minerals.

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Root hair cells

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A solid that dissolves in a liquid.

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Solute

Front 54

A structure consisting of protein fibres found in eukaryotic cells during cell division. They guide the movement of chromosomes to opposite end of the cell at telophase.

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Spindle

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Flattened membrane sacs in chloroplasts, which hold the pigments used in photosynthesis and are the site of the light reactions. A stack of these forms a granum.

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Thylakoid

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A membrane-bound sac found in cells and used to transport materials around the cell.

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Vesicle

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A measure of the ability of water molecules to move freely in solution. Decreased by the presence of solutes.

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Water potential

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A plant tissue containing vessels (and other cells) that are used to transport water in a plant and provide support.

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Xylem

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A version of a gene.

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Allele

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In mitosis, the stage when the newly separated chromatids are pulled towards opposite poles of the nuclear spindle.

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Anaphase

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The production of genetically identical new organisms by a single ‘parent’ organism.

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Asexual reproduction

Front 62

Airways in the lungs that lead from the trachea to the bronchioles.

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Bronchi

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Airways in the lungs that lead from the bronchi to the alveoli.

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Bronchioles

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The process by which known concentrations of a substance in a solution are used to make a standard curve on a graph. This can be used to determine the amount of that substance in solutions of unknown concentration.

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Calibration

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To determine the value of intervals of a scale on an instrument, such as a thermometer.

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Calibration

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Plant tissue in the stem and root that contains dividing cells.

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Cambium

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A class of biological molecules with the general formula (CH2O)n. It includes sugars, starches, glycogen and cellulose.

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Carbohydrate

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Processes that lead to communication and coordination between cells. Hormones binding to their receptors on the cell surface membrane are an example.

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Cell signalling

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A carbohydrate polymer (of beta-glucose) that forms plant cell walls.

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Cellulose

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An organelle from which the spindle fibres develop during cell division in animal cells.

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Centriole

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The region of a chromosome where two sister chromatids are joined together, and where the spindle fibre attaches during cell division.

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Centromere

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A lipid molecule found in all cell membranes that affects membrane fluidity and is involved in the synthesis of steroid hormones.

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Cholesterol

Front 73

A replicated chromosome appears as two strands in early stages of cell division. Each strand is called a…..

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Chromatid

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Lining cells that have cilia on their cell surface.

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Ciliated epithelium

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Genetically identical cells or individuals.

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Clones

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An organic non-protein molecule that binds temporarily with substrate to an enzyme active site. It is essential for enzyme activity.

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Coenzyme

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A structural fibrous protein found in connective tissue, bones, skin and cartilage. It accounts for 30% of body protein.

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Collagen

Front 78

A cell in the phloem involved in actively loading sucrose into the sieve tube elements, to which it is linked by many plasmodesmata.

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Companion cell

Front 79

Refers to structures that fit together because their shapes and/or charges match up. For example, adenine and cytosine in DNA.

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Complementary

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The difference in amount of a substance between two regions results in this.

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Concentration gradient

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A type of tissue that consists of separate cells held together by a ground substance (matrix).

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Connective tissue

Front 82

State of animal cells when they have been immersed in a solution of lower water potential and have lost water by osmosis and become shrivelled.

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Crenation

Front 83

The division of the cell, following nuclear division, to form two new cells.

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Cytokinesis

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The network of protein fibres and microtubules found within the cell that gives structure to the cell and is responsible for the movement of many materials within it.

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Cytoskeleton

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The difference in molecular concentration that allows diffusion to occur.

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Diffusion gradient

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Cells or organisms that have two copies of each chromosome in their nuclei.

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Diploid

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The process of taking materials into a cell by surrounding them with plasma membrane, which pinches off to form a vesicle inside the cell. This is an active process requiring ATP.

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Endocytosis

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Outer layer(s) of cells of a multicellular organism.

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Epidermis

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A tissue that covers the outside of a structure.

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Epithelium

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Red blood cells.

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Erythrocytes

Front 91

The process of removing materials from the cell by fusing vesicles containing the material with the plasma membrane .

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Exocytosis

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The passive movement of molecules across membranes down their concentration gradient. Aided by transport proteins but no metabolic energy is required.

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Facilitated diffusion

Front 93

The model of cell membrane structure proposed by Singer and Nicholson – a phospholipid bilayer with proteins ‘floating’ in it.

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Fluid mosaic

Front 94

All the genetic material inside an organism (or cell).

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Genome

Front 95

A lipid with carbohydrate molecules attached.

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Glycolipid

Front 96

In pairs, these form the stomatal pore in the epidermis plants. They control the opening and closing of the pore by changes in their turgidity.

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Guard cell

Front 97

The protein that carries oxygen in the red blood cells.

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Haemoglobin

Front 98

The rupturing of animal cell surface membranes, and subsequent release of their contents, when cells placed in a solution of higher water potential and water enters by osmosis.

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Haemolysis

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Chromosomes in diploid organisms that have the same genes at the same loci and that pair up during meiosis. Can also refer to structures that have a common evolutionary origin.

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Homologous

Front 100

The phase of the cell cycle where synthesis of new DNA and organelles takes place.

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Interphase

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A waterproofing substance that impregnates the walls of xylem tissue and gives wood its strength.

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Lignin

Front 102

A diverse group of chemicals that includes triglycerides, fatty acids and cholesterol.

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Lipid

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A cavity surrounded by a cell wall in cells, such as xylem vessels, which have lost their cell contents. Also used for the central cavities of blood vessels.

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Lumen

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The number of times greater an image is than the object.

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Magnification

Front 105

Nuclear division that results in the formation of cells containing half the number of chromosomes of the adult cell.

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Meiosis

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A type of RNA polynucleotide involved in protein synthesis. Carries the information coding for a polypeptide from the nucleus to the ribosomes in the cytoplasm.

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Messenger RNA

Front 107

The phase of mitosis where the chromosomes line up at the equator of the spindle.

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Metaphase

Front 108

Proteins associated with microtubules. The proteins can move along microtubules. Kinesin moves towards the (+) end of the microtubules and dynein moves towards the (–) end.

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Microtubule motors

Front 109

Components of the cell cytoskeleton. Involved in mitosis, cytokinesis and movement of vesicles within cells.

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Microtubules

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Folds in the membrane of a cell that increase its surface area.

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Microvilli

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A slimy substance secreted by goblet cells in animal epithelial tissues. It is made up mostly of glycoproteins and protects and/or lubricates the surface on to which it is secreted.

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Mucus

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A change in the structure of DNA resulting in a change in the sequence of bases. Can refer to a change in in the structure or number of chromosomes.

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Mutation

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The double membrane structure surrounding the nucleus in eukaryotic cells.

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Nuclear envelope

Front 114

The total substances taken into an animal or plant for use in metabolism.

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Nutrition

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Term used to describe stem cells that retains the ability to differentiate into any other of the organism's cells.

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Omnipotent

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A collection of tissues that work together to perform a specific overall function or set of functions within a multicellular organism.

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Organ

Front 117

Relatively unspecialised plant cells. They have living contents and thin, permeable cellulose cell walls. They may be able to photosynthesise, store food or support young plants.

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Parenchyma

Front 118

A cell that can ingest bacteria or small particles. Macrophages and neutrophils are examples of this.

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Phagocyte

Front 119

A tissue in plants that is used to transport dissolved sugars and other substances.

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Phloem

Front 120

A molecule consisting of a glycerol molecule, two fatty acid molecules and a phosphate group covalently bonded together. Forms the basis of cell membranes.

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Phospholipid

Front 121

A large molecule made up of many/repeating similar, smaller molecules (monomers) covalently bonded together.

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Polymer

Front 122

The phase of mitosis where the chromosomes become visible as a pair of sister chromatids joined at the centromere.

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Prophase

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The ability in microscopy to distinguish two separate points as distinct from each other.

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Resolution

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A single-stranded polynucleotide molecule that exists in three forms. Each form plays a part in the synthesis of proteins within cells.

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RNA

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The replication of a DNA strand where the replicated double helix consists of one old strand and one newly synthesised strand.

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Semi-conservative replication

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Production of a new individual formed by the fusing of gametes from two different parents so that the offspring have a unique combination of alleles from both parents.

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Sexual reproduction

Front 127

A cell in phloem tissue through which sap is transported. It has very little cytoplasm, no nucleus, and non-thickened cellulose cell walls, with the end walls perforated.

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Sieve tube element

Front 128

The component of water potential that is due to the presence of dissolved substances.

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Solute potential

Front 129

Liquid with dissolved solids.

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Solution

Front 130

A liquid that dissolves solids.

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Solvent

Front 131

Pore in leaf epidermis, surrounded by two guard cells. Changes in turgidity of the guard cells can open or close the stoma. Allows gaseous exchange and transpiration in plants.

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Stoma

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The gel-like matrix found in chloroplasts. The membranes of the thylakoids/grana are embedded in it.

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Stroma

Front 133

Final phase of mitosis. Two new nuclear envelopes form around the two new nuclei.

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Telophase

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Undifferentiated cell that is capable of differentiating into any kind of specialised cell.

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Totipotent/omnipotent

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The windpipe leading from the back of the mouth to the bronchi.

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Trachea

Front 136

The detailed structure of the internal components of cells as revealed by the electron microscope rather than by the light microscope.

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Ultrastructure

Front 137

Diploid cell made from fusion of male and female gametes.

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Zygote

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Fluid portion in centre of mitochondrion.

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Matrix

Front 139

Used to increase contrast in light microscopy.

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Staining

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Region of endoplasmic reticulum free of ribosomes. Site of lipid synthesis.

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Smooth ER

Front 141

Stacks of membranes in the chloroplast where light energy is collected for photosynthesis.

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Granum

Front 142

Denser staining region within the nucleus where ribosome assembly occurs.

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Nucleolus

Front 143

Whip-like organelle that is used for cellular locomotion by bacteria. Some protists and gametes have similar stuctures (undulipodia).

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Flagella

Front 144

Eukaryotic flagellum - has a different structure to bacterial flagellae.

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Undulipodia

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Ill-defined region in bacterial cell where chromosome is located.

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Nucleoid

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Short hair-like appendages found on the surface of bacteria. Help with DNA exchange (conjugation), locomotion and adhesion.

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Pili

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Extra coat of polysaccharide outside the cell wall carried by some bacteria.

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Capsule

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Strcuture adopted by phospholipids that gives membranes their properties.

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Bilayer

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The type of cell that responds to a particular hormone.

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Target cell

Front 150

Made up of interphase and mitosis, this refers to the process of cell multiplication.

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Cell cycle

Front 151

A large plant organelle involved in storing cell sap and regulating turgor pressure.

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Vacuole