Organisms and Life Processes - Unit 1 Overview

Flashcards covering vocabulary and key concepts from the 'Life Processes' and 'Variety of Living Organisms' lecture notes, focusing on cell structure, enzymes, respiration, transport methods, and organization.

Cells

The microscopic building blocks that all living organisms are composed of.

Nutrition

The life process where plants make their own food or animals eat other organisms.

Respiration

The chemical process of releasing energy from food, which happens in all cells of the body.

Excretion

The life process of getting rid of waste products produced by the body.

Movement

Achieved by the action of muscles in animals and by slow growth movements in plants.

Sensitivity to stimuli

The ability of organisms to respond to changes in their surroundings.

Internal Control

The ability of an organism to maintain steady states inside the body, such as temperature or water content.

Reproduction

The process by which living organisms produce offspring.

Growth and Development

The increase in size and complexity of an organism using materials from food.

Multicellular

Organisms that are composed of millions of cells, often showing hundreds of different specialised types.

Cytoplasm

The living material that makes up a cell, having a complex texture between a solid and a liquid.

Organelles

Detailed structures found within the cytoplasm of a cell, visible under an electron microscope.

Nucleus

The largest organelle that controls the activities of the cell and contains the genetic material.

Chromosomes

Structures found in the nucleus that carry genes; human cells contain $46$ of them.

Ribosomes

Tiny structures in the cytoplasm, roughly $25\text{ nm}$ in diameter, where proteins are assembled.

Enzymes

A group of proteins that act as biological catalysts to control chemical reactions in the cell.

Cell Membrane

A thin layer forming a boundary between the cytoplasm and the outside, described as being selectively permeable.

Selective Permeability

The ability of a membrane to control the movement of specific substances into and out of the cell.

Mitochondria

Organelles where most of the energy from respiration is released; plural is mitochondria, singular is mitochondrion.

Cell Wall

A layer of non-living, tough material made of cellulose found outside the cell membrane of plant cells.

Freely Permeable

A term describing walls like the cellulose cell wall, which are not a barrier to water or dissolved substances.

Vacuole

A permanent feature in mature plant cells filled with cell sap, acting as a store for dissolved sugars and mineral ions.

Chloroplasts

Organelles in the green parts of plants that contain chlorophyll and absorb light for photosynthesis.

Chlorophyll

The green pigment found inside chloroplasts.

Catalyst

A chemical that speeds up a reaction without being used up or changed itself.

Substrate

The specific molecule that an enzyme acts upon.

Active Site

The small area on an enzyme's surface where the substrate attaches for a reaction to occur.

Lock and Key Model

The model describing how a substrate fits perfectly into an enzyme's active site based on its specific shape.

Metabolism

The sum of all the chemical reactions taking place inside a cell.

Intracellular Enzymes

Enzymes that stay inside the cell to carry out their functions.

Extracellular Enzymes

Enzymes secreted outside of cells to function, such as digestive enzymes in the intestine.

Optimum Temperature

The 'best' temperature for an enzyme, which in humans is approximately $37\text{ }^{\circ}C$.

Kinetic Energy

The energy an object has due to its movement; higher temperatures increase this in enzyme and substrate molecules.

Denatured

The permanent change in the shape of an enzyme's active site caused by excessive heat, preventing it from functioning.

Optimum pH

The specific pH at which an enzyme works best; for most cells this is $pH\text{ }7$.

ATP (Adenosine Triphosphate)

The chemical 'currency' used by cells to transfer energy between respiration and other cellular processes.

Aerobic Respiration

The process described by the equation: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O (+ \text{energy})$.

Anaerobic Respiration (Yeast)

Partial breakdown of glucose without oxygen described as: $\text{glucose} \rightarrow \text{ethanol} + \text{carbon dioxide} (+ \text{some energy})$.

Anaerobic Respiration (Muscle)

The breakdown of glucose in overworked muscles described as: $\text{glucose} \rightarrow \text{lactate} (+ \text{some energy})$.

Oxygen Debt

The volume of oxygen required to oxidise the lactate built up in the body during anaerobic respiration.

Diffusion

The net movement of molecules or ions from a region of high concentration to a region of low concentration.

Active Transport

The movement of substances against a concentration gradient using energy from respiration and protein pumps.

Osmosis

The net movement of water from a dilute solution to a more concentrated solution across a partially permeable membrane.

Differentiation

The process by which the structure of a cell becomes specialised to carry out a particular function.

Mitosis

The type of cell division where a cell divides into two identical daughter cells for growth and repair.

Tissue

A group of cells with similar functions working together.

Organ

A collection of several different tissues carrying out a particular function.

Stem Cell

An undifferentiated cell with the ability to divide many times and differentiate into specialised cells.

Embryonic Stem Cells

Stem cells found in early embryos that retain the ability to differentiate into any cell type.

Adult Stem Cells

Stem cells found in tissues like bone marrow that can only produce a limited number of specialised cell types.

Resolution

The ability to distinguish two points in an image as being separate; for light microscopes this is about $200\text{ nm}$.