Biology Cells Vocab

Demonstrate understanding of life processes at the cellular level - 91156

Activation energy

The energy required for a chemical reaction to occur

Active site

A region on an enzyme which a substrate binds to during a reaction

Active transport

Movement of ions or molecules across a membrane by proteins, against a concentration gradient. Requires energy

Aerobic Respiration

An enzyme-controlled process that occurs in the mitochondria and produces energy in the form of ATP in the presence of oxygen

Glucose + oxygen → carbon dioxide + water + energy (36 ATP).

Allele

An alternative form of a gene

Anabolic

Reactions that join substrates together

Anaerobic respiration

Glucose is broken down in the absence of oxygen into lactic acid and ATP in the cytoplasm.

Glucose-> Lactic acid + 2ATP

Autosomes

Chromosomes other than those concerned with sex determination

Cell membrane

Semi-permeable, phospholipid bilayer that controls entry and exit of substances into and out of cells

Cell wall

Hard structure made of cellulose that gives plant cells support

Centrioles

A pair of structures in animal cells involved in making the spindle during cell division

Centromere

The region where two sister chromatids are joined and attach to the spindle during cell division

Characteristics

A feature of an organism (trait/phenotype)

Chloroplast

Organelle in some plant cells that is involved in photosynthesis

Chromosome

A unit of genetic material made of DNA wound around histone proteins

Coenzyme

An organic molecule that is necessary for an enzyme to function and participates in the chemical reaction but is left unchanged after the reaction

Co-factor

A metal ion that completes an enzyme's active site

Compartmentalisation

In both mitochondria and chloroplasts, specific chemical reactions are isolated by membranes from other reactions to increase the efficiency of the reaction

Cytoplasm

Jelly-like material in the cells of plants and animals, composed of water, salts, and various organic molecules

Denature

Where an enzyme, due to heat or pH, has its active site permanently altered so that substrates can no longer 'fit' the active site, and the biological reaction stops

Diffusion

The random, passive movement of particles from an area of high concentration to an area of low concentration until they reach equilibrium

DNA/ Deoxyribonucleic acid

Genetic material in the form of a double-stranded, helix shaped molecule containing the genetic code. Contains a deoxyribose sugar and phosphate backbone, and bases A,T,G,C.

DNA Replication

Process prior to cell division where DNA is copied so that new daughter cells will have the same genetic information.

Endocytosis

The process by which cells take in substances from outside the cell by engulfing them in a vesicle. A form of active transport

Endoplasmic reticulum

A network of membranes found throughout the cytoplasm of cells, which are involved in processing proteins (Rough ER) and lipids (Smooth ER)

Enzyme

A globular protein which acts as a biological catalyst to speed up the rate of a chemical reaction in an organism

Exocytosis

A vesicle membrane fuses with a cell membrane to expel its contents out of the cell

Fertilisation

The combining of the sperm and egg to form a single-celled zygote

Gametes

Sex cells containing half the chromosomes of the parent.

Gene

A section of DNA that codes for a protein.

Genetic diversity/variation

The total number of different alleles in the genetic makeup of a breeding population

Glycolysis

Glucose is broken down in the cytoplasm without the presence of oxygen and two molecules of ATP are made

Golgi apparatus

Organelle that processes and packages proteins into a usable form to be exported out of the cells

Inhibitor

Toxins that bind to, or distort, the active site and prevent the enzyme from catalysing reactions

Ion pumps

A form of active transport where plasma membranes can pump ions against a concentration gradient. E.g. Na+ and K+

Krebs cycle

A part of aerobic respiration where the product of glycolysis enters the matrix of the mitochondrion and undergoes a series of enzymatic reactions. Hydrogen is removed and carbon dioxide is excreted

Leading strand

The daughter strand of DNA that is copied continuously during DNA replication in the direction that the replication fork is moving

Lysosome

Organelle containing digestive enzymes that will recycle chemicals and worn-out organelles

Meiosis

Cell division during sexual reproduction, where gametes are formed by halving the genetic information of the original cell and creating different combinations of alleles from the parents, introducing variation

Mitochondrion

Organelle in animals and plants where respiration takes place to release energy for the cell

Mitosis

Cell division for growth, repair, and maintenance in somatic cells, where one parent cell divides into two genetically identical daughter cells

Nuclear membrane

Double-layered membrane with pores to allow transfer of substances between the nucleus and the cytoplasm

Nucleus

An organelle that holds the chromosomes and controls cell activity

Offspring

The resulting individuals of reproduction

Okazaki fragments

The name of the lagging strand fragments made during DNA replication

Osmosis

The passive diffusion of water from an area of higher water concentration to an area of lower water concentration, across a semi-permeable membrane

Passive transport

Includes diffusion, osmosis, and facilitated diffusion. No energy is required for this to occur, and particles move from high to low concentration

Phagocytosis

A form of active transport where particles are engulfed by a membrane that wraps around them, taking them into the cell in vesicles

Pinocytosis

A form of active transport where liquid is engulfed by a membrane wrapping around it and taking it into the cell in vesicles

Phenotype

How a gene is expressed as a protein/characteristic/trait

Photosynthesis

The process of plants making glucose with light energy in the chloroplasts.

Water + carbon dioxide -light-> glucose + oxygen

Plasmolysis

The irreversible process whereby plant cells lose too much water, causing the cell membrane to shrink away from the cell wall

Respiration

Cellular process in the mitochondria where glucose is broken down to release energy in the form of ATP

Ribosomes

Made of RNA and used in the production of proteins

Rough E.R

Studded with ribosomes, this region produces proteins which are then transported to other organelles in the cell

Semi-conservative replication

New DNA molecules after replication consist of one parental strand from the original molecule and one newly synthesized daughter strand

Sex chromosomes

Chromosomes involved in sex determination. E.g., X and y in mammals

Sexual reproduction

The combining of genetic information from two parents resulting in genetically unique offspring

Smooth E.R.

Involved with lipid metabolism, steroid synthesis, and detoxification in the liver

Trait

A feature of an organism (protein/phenotype/characteristic)

Vacuole

These organelles store materials like water and starch granules. Larger and more numerous in plants

Zygote

The fertilised egg/ovum

Anti-parallel

Describes how the two backbones of DNA run in opposite directions - one 3'-5' and the other 5'-3'. Explains why there is a leading strand and a lagging strand in DNA replication.

ATP (Adenosine Triphosphate)

The molecule in all living cells that stores and releases energy for cellular processes

Catabolic

Reactions that break molecules down. For example, digestion

Chlorophyll

A green pigment essential for absorbing light energy during photosynthesis

Cristae (singular: crista)

The folds in the inner mitochondrial membrane increase the surface area where the electron transfer chain occurs

Electron Transport Chain

Occurs in the cristae of the mitochondria. Hydrogen produced in the Krebs cycle is passed along a chain to form a large amount of ATP. Oxygen is required to pick up the hydrogen ions at the end to form water

Facilitated diffusion

Passive transport of substances through channel proteins across a membrane from an area of higher concentration to an area of lower concentration

Flaccid

A state where cells lack turgor pressure due to water loss, meaning they are soft, limp, and lacking firmness

Hypertonic solution

A solution with a comparatively higher concentration of solutes compared to another

Hypotonic solution

A solution with a comparatively lower concentration of solutes compared to another

Induced fit model

The model of enzyme action that states that since enzymes are flexible structures, binding of the substrate to the enzyme alters the shape of both the enzyme and the substrate, providing a better fit and, in so doing, reducing the activation energy for the reaction required

Isotonic solution

A solution with the same concentration of solutes compared to another

Lactic acid

A toxic compound produced in animals during anaerobic respiration

Lagging strand

The daughter strand of DNA that is copied in segments called Okazaki fragments during DNA replication against the direction that the replication fork is moving, due to the anti-parallel nature of the DNA helix.

Large vacuole

Large, water-filled organelle within a plant cell cytoplasm

Light-dependent reaction

Stage of photosynthesis that occurs in the thylakoid where water is split using light energy

Light-independent reaction

Enymatic reactions that occur in the stroma of the chloroplast during photosynthesis that do not rely on energy from sunlight.

Lock and key model

The model of enzyme action that states the substrate fits into the enzyme's active site (like a key fitting into a lock) to form an enzyme-substrate complex

Lysis

Cell membrane bursts due to excessively high water pressure

Metabolism

All of the biochemical reactions happening in the cells of an organism

Mitochondrial

Matrix The innermost compartment of a mitochondrion, enclosed by the inner mitochondrial membrane. It contains various enzymes and other essential components involved in cellular respiration

Organelle

An organised and specialised structure found within cells

Semi-permeable membrane

A membrane that allows some substances to pass through it but not others

Stomata

Microscopic openings on a leaf surface that permit gas exchange

Stroma

The fluid that fills up the inner space of the chloroplasts which encircles the grana and the thylakoids. Where the light-independent reactions of photosynthesis occur

Substrate

A molecule upon which an enzyme acts. (Reactant(s) of an enzyme-catalysed reaction)

Tonicity

It refers to the relative concentration of solutes (dissolved substances) on either side of a cell membrane in osmosis

Turgid

Refers to cells or tissues that are swollen from water uptake

Water potential

The concentration of water in a solution. It can be high, low, or in equilibrium