GCSE Biology Topic 1

Cell

Basic unit of life

Prokaryotic

Cells that do not have a nucleus (Bacteria)

Prokaryote

A prokaryotic cell (single celled organism)

Eukaryotic

Cell with a nucleus (All plant and animal cells)

Eukaryote

An organism made up of eukaryotic cells

Nucleus

The part of the cell containing DNA and RNA and responsible for growth and reproduction

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Cell membrane

A thin, flexible barrier around a cell; regulates what enters and leaves the cell

Mitochondria

An organelle in which respiration and energy production occur

Ribosomes

Where proteins are made

Cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell

Vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Chloroplast

Where photosynthesis occurs, making food. Full of green chlorophyll

Plasmid

A small ring of DNA

Animal cell parts

Nucleus, Cytoplasm, Cell membrane, Mitochondria, Ribosomes

Plant cell parts

Nucleus, Cytoplasm, Cell membrane, Mitochondria, Ribosomes, Cell wall, Vacuole, Chloroplast

Bacteria cell parts

Cytoplasm, Cell membrane, Cell wall, Plasmids, Single circular strand of DNA

Microscope

Used to see things too small to see with the naked eye

Light microscope

Uses light and lenses to magnify a specimen, used to view individual cells and large sub-cellular structures

Electron microscope

Uses electrons to form a highly magnified image of a specimen, used to view small sub-cellular structures like the insides of chloroplasts and mitochondrias

Magnification

Image size / Real size

Differentiation

The process by which a cell changes to become specialised for its job

Sperm Cell

The cell specialised for reproduction

Nerve Cell

The cell specialised for rapid signalling

Muscle Cell

The cell specialised for contraction

Root Hair Cell

The cell specialised for absorbing water and minerals

Phloem and Xylem Cells

The cells specialised for transporting substances

Chromosomes

A cellular structure carrying genetic material, found in the nucleus consisting of one very long DNA molecule and associated proteins

2 copies

Each chromosome has _______________ (one from the father, one from the mother)

23

Humans have ___ pairs of chromosomes

Cell cycle

Makes new cells for growth, development and repair. Only happens in eukaryotic cells

Cell cycle stage 1

DNA is spread out in to long strings

Cell cycle stage 2

Before dividing, the cell grows to increase the number of organelles

Cell cycle stage 3

The cell duplicates its DNA (one for each new cell) and forms X shaped chromosomes

Cell cycle stage 4

The chromosomes line up at the centre of the cell to be pulled apart by cell fibres

Cell cycle stage 5

Membranes form around each set of chromosomes, forming nuclei

Cell cycle stage 6

The cytoplasm and cell membrane divide and 2 identical daughter cells have been created

Binary Fission

A form of asexual reproduction in which one prokaryotic cell (single celled organism) divides to form two identical cells.

Binary Fission stage 1

The circular DNA and plasmid replicate

Binary Fission stage 2

The cell gets bigger and the circular DNA strands move to opposite ends of the cell

Binary Fission stage 3

The cytoplasm begins to divide and new cell walls form

Binary Fission stage 4

The cytoplasm divides and 2 daughter cells are created. Each cell has one copy of the circular DNA but can have a variable number of copies of plasmid

Stem cell

Unspecialized cells that retain the ability to become a wide variety of specialized cells

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

Diffusion of water through a selectively permeable membrane

Active Transport

The movement of materials through a cell membrane using energy.

Exchange substances

Organisms ________________ with their environment

Exchange surface

A specialised area adapted to make it easier for molecules to cross from one side of the surface to the other

Features of the alveoli

-Enormous surface area

-Moist lining

-Thin walls

-Good blood supply

Alveoli

Terminal air sacs that constitute the gas exchange surface of the lungs.

Lungs

The organ for putting oxygen into the bloodstream and taking carbon dioxide out