cell structure

prokaryotes are simpler organisms

bacterial cells are much smaller than plant cells

cell membrane

site of chemical reactions in the cell

it is a Gell like substance containing enzymes to catalyse the reactions.

bacterial DNA

Floats in the cytoplasm

it controls the functions of a cell

cell wall

is not made of cellulose

it supports and strengthen the cell

plasmid

are small rings of DNA

it contains additional genes

cytoplasm

semi permeable

controls the movement of substances in and out of the cell

specialised cells

specialised animal cells

specialised plant cells

nerve

carries electrical signals

long branches connections and insulating sheath

1200px-Neuron.svg

sperm

fertilises an egg

streamlined with a long tail, acrosome containing enzymes, large number of mitochondria

sperm-cell

muscle

contracts to allow movement

contains a large number of mitochondria

56712527-smooth-muscle-tissue-anatomy-of-a-relaxed-and-contracted-smooth-muscle-cell

root hair cell

absorbs water and minerals from soil

xylem

phloem

carries glucose

carries water and minerals

hair like projections to increase surface area

TRANSPIRATION - dead cells cell walls toughened by lignin and flows in one direction

2778302_orig

TRANSCOLATION - living cells cells have end plates with holes and flows in both directions

xylem__phloem

1433456238

cell differentiation

animal cell differentiation

how a cell changes and becomes specialised , undifferentiated cells are called stem cells

plant cell differentiation

early stages of development only for repair and replacement

all stages of life cycle the system cells are grouped together in meristems

microscopy

magnification (m) = size of image (i) divided by real size of the object (a)

electron beams

light rays

radiation used

~ 2 000 000

~ 1500

Max Magnification

0.2nm

200nm

Resolution

very large and not possible

small and portable

size of microscope

several £100,000 to £1 million plus

~£100 for a school one

cost

prefixes

milli (mm)

centi (cm

micro (um)

nano (nm)

1 cm = 0.01m

x10-2

1mm = 0.001m

x10-3

1um = 0.000001m

x10-6

1nm = 0.000000001m

x10-9

eukaryotes complex organisms

animal cell

plant cell

cytoplasm

site of chemical reactions in cell

gel like substance contains enzymes to catalyse the reactions

nucleus

contains genetic material

controls the activities of the cell and codes for proteins

cell membrane

semi permeable

controls the movement of substances in and out of the cell

ribosome

site of protein synthesis

MRNA is translated into an amino acid chain

permanent vacuole

contains cell sap

keeps cell turgid, contains sugars and salts in solution

cell wall

made of cellulose

supports and strengthens the cell

chloroplatsts

site of photosynthesis

contains chlorophyll, absorbs light energy

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