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Level 2 Biology > Definitions > Flashcards

Flashcards in Definitions Deck (33):
1

Organelle

Organelles are specialised parts of a cell that have specific functions.

2

Cell Membrane

The cell membrane encloses the cytoplasm of the cell and controls what enters and exits the cell.

3

Cytoplasm

The cytoplasm is a jelly like, nutrient rich substance where organelles are located. This is also where many of the reactions of the cell occur, like glycolysis.

4

Nucleus

Often called the 'control centre,' the nucleus contains the DNA which controls and regulates the function of the cell. Within the nucleus is the nucleolus, which produces the RNA used in protein synthesis.

5

Mitochondrion

The mitochondrion is responsible for producing ATP from glucose and oxygen during aerobic respiration.

6

Endoplasmic Reticulum

The ER is a series of tubes bound to the nuclear membrane, and can be categorised into two seperate types:
Rough ER - Studded with ribosomes and involved in protein production
Smooth ER - Lacking ribosomes and involved in the synthesis of lipids

7

Ribosome

Ribosomes are responsible for protein synthesis, and can either be attached to the rough endoplasmic reticulum or float freely in the cytoplasm of the cell.

8

Golgi Body

The Golgi Body is the 'packaging centre' of the cell. Molecules synthesised by the ER are transferred to the Golgi Body, where they are folded and joined to other molecules before being packaged into a vesicle and sent out of the cell.

9

Lysosome

The lysosome contained digestive enzymes which can break down unwanted molecules within the cell, such as worn out organelles or foreign bacteria engulfed by the white blood cells.

10

Cristae

The complex series of folds within the mitochondria.

11

Krebs Cycle

The sequence of reactions by which most living cells generate energy during the process of aerobic respiration.

12

RNA

RNA stands for Ribonucleic Acid, an acid present in all living cells. It's principal role is to act as a messenger, carrying instructions from DNA for controlling the synthesis of proteins.

13

ATP

ATP stands for Adenosine Triphosphate and is the energy currency of life. ATP is a high energy molecule found in every cell. it's job is to store and supply the cell with needed energy.

14

Vacuole

A vacuole is a membrane bound sac filled with fluid. Both animal and plant cells contain a vacuole, however this is considerably larger in a plant cell and takes up most of the cell.

15

Chloroplast

The chloroplast is an organelle containing chlorophyll and is where photosynthesis occurs.

16

Chlorophyll

The compound that makes plants green.

17

Cell Wall

The cell wall is the main defining feature between an animal and plant cell. This provides structure to the plant and is outside the cell membrane.

18

Palisade Cells

Palisade cells are a specialised type of plant cell. They are vertically elongated and packed closely together.

19

Diffusion

The net movement of particles from an area of high concentration to an area of low concentration.

20

Osmosis

The spontaneous net movement of water molecules across a semi permeable membrane from areas of lower solute concentration to areas of higher solute concentration.

21

Semi Permeable Membrane

A semi permeable membrane is a type of biological membrane that will allow certain molecules or ions to pass through it via a transport mechanism (diffusion, osmosis, facilitated diffusion or active transport).

22

Tonicity

The relative concentration of solutes dissolved in solution which determine the direction and extent of diffusion.

23

Hypotonic

Having a lower osmotic pressure than a particular fluid.

24

Hypertonic

Having a higher osmotic pressure than a particular fluid.

25

Isotonic

Having the same osmotic pressure as another fluid.

26

Osmotic Pressure

The pressure that would have been applied to a pure solvent to prevent it from passing into a given solution by osmosis and is often used to express the concentration of a solution.

27

Facilitated Diffusion

Facilitated diffusion is the process of spontaneous passive transport of molecules or ions across a cell's membrane via specific transmembrane integral proteins.

28

Active Transport

Active transport is the movement of molecules across a cell membrane against their concentration gradient.

29

Cytosis

Cytosis is a transport mechanism for the movement of large quantities of molecules in and out of cells.

30

Endocytosis

Endocytosis is a form of active transport in which cells absorb large molecules by engulfing them.

31

Phagocytosis

Phagocytosis is a type of endocytosis, by which relatively large particles, such as cell debris and micro organisms, are internalised by the cell.

32

Pinocytosis

Pinocytosis is a type of endocytosis, it is a process which takes in small molecules, including water, from extracellular fluid.

33

Exocytosis

Exocytosis is the exact opposite of endocytosis, by which the intracellular vesicle containing the substance to be expelled fuses with the cell membrane to expel the contents of the vesicle into the extracellular fluid.