biology - ch2: cells

define cells

cells are the smallest units from which all organisms are made

what does unicellular mean? give 2 examples of unicellular organisms

unicellular means the organism is made of just a single cell. examples include bacteria and yeast

cellular differences between plant and animal cells [3]

1. plant cells have cell walls made of cellulose whereas animal cells don’t have cell walls

2. plant cells have chloroplasts containing chlorophyll whereas animal cells dont

3. plant cells have large vacuoles containing cellular sap whereas animal cells have much smaller vacuoles called vesicles

how are new cells produced?

by division of existing cells

cell membrane [3]

1. partially permeable so controls what goes in and out of the cell

2. made of proteins and lipids

3. separates the content of the cell from the rest of its surroundings

cell wall [3]

1. fully permeable

2. made of fibres through which bigger molecules can pass through

3. prevents cell from bursting when it absorbs too much water

cytoplasm [2]

1. clear, jelly-like substance

2. about 70% water, therefore metabolic reactions take place here

vacuole [3]

1. fluid filled space inside a cell surrounded by its own membrane

2. animal cell - small, called vesicles

3. plant cells - large and permanent, when full presses outwards on rest of cell which keeps it in shape

nucleus [2]

1. contains the DNA of the organism in the form of chromosomes

2. controls what the cell does

chloroplasts [2]

1. contain chlorophyll

2. contain starch grains (made during photosynthesis)

mitochondria

helps carry out aerobic respiration to release energy from glucose

ribosomes

help in protein synthesis

what are bacterica? [2]

unicellular organisms that don't have a nucleus

what are cells walls of bacterial cells made of?

peptidoglycan

differences between plant/animal cells and bacterial cells [3]

1. no nucleus

2. no chloroplasts

3. no mitochondria

what are plasmids

smaller circles of DNA

specialised cells have ______ _______

specific functions

ciliated cell found in and function

1. found in linings of trachea and bronchi in animals

2. moves mucus in trachea bronchi

neuron found in and function

1. found in the nervous system of animals

2. conducts electrical impulses

red blood cells found in and function

1. found in blood of mammals

2. transports oxygen

root hair cell found in and function

1. found in tips of roots of flowering plants

2. absorbs water and mineral ions

palisade mesophyll cell found in and function

1. found in the leaves of flowering plants

2. photosynthesis

sperm + egg cells found in and function

1. found in testes and ovaries of mammals
2. gametes used in reproduction

define tissue

a group of similar cells that work together to perform a particular function

define organ

a group of tissues that work together to perform a specific function

define organ system

several organs that work together to perform a specific function

magnification

magnification = image/actual

how many micrometres in an mm

1000