Cell Structure and Division

Nucleus

contains DNA and controls cell activities

Cytoplasm

where most chemical reactions occur

Cell membrane

controls movement of substances into and out of the cell

Mitochondria

site of aerobic respiration and energy release

Ribosomes

site of protein synthesis

Plant cell structures not found in animal cells

cell wall chloroplasts and permanent vacuole

Cell wall

strengthens and supports the cell

Cell wall composition

cellulose

Chloroplasts

site of photosynthesis

Pigment in chloroplasts

chlorophyll

Permanent vacuole

contains cell sap and keeps the cell turgid

Specialised cell

a cell adapted for a specific function

Sperm cell adaptations

tail for movement many mitochondria and acrosome with enzymes

Function of sperm cell

fertilise an egg cell

Egg cell adaptations

large cytoplasm containing nutrients

Nerve cell adaptations

long axon to carry impulses over long distances

Function of nerve cell

transmit electrical impulses

Muscle cell adaptations

many mitochondria for energy release

Root hair cell adaptations

large surface area for water and mineral uptake

Why root hair cells contain many mitochondria

to provide energy for active transport

Xylem cell adaptations

hollow tubes with strengthened walls for water transport

Phloem cell adaptations

forms tubes to transport sugars around the plant

Microscope

used to magnify small objects

Highest magnification microscope

electron microscope

Microscope producing colour images

light microscope

Magnification

how many times larger an image appears than the actual object

Magnification equation

image size ÷ actual size

Resolution

ability to distinguish between two close points

Cell cycle

stages a cell goes through before division

Main stages of cell cycle

growth DNA replication and mitosis

Mitosis

cell division producing two genetically identical daughter cells

Number of daughter cells produced by mitosis

two

Daughter cells after mitosis

genetically identical

Importance of mitosis

growth repair and replacement

What happens before mitosis

DNA is copied

Chromosomes

coiled DNA molecules carrying genetic information

Location of chromosomes

nucleus

Stem cells

unspecialised cells that can divide and differentiate

Differentiation

process by which a cell becomes specialised

Embryonic stem cells location

embryos

Why embryonic stem cells are useful

can become any type of body cell

Adult stem cells location

bone marrow and some tissues

Adult stem cell ability

can form a limited range of specialised cells

Use of stem cells

treatment of diseases such as leukaemia

Benefit of stem cell therapy

may replace damaged cells

Ethical issue with embryonic stem cells

destruction of embryos

Levels of organisation

cell tissue organ organ system organism

Tissue

group of similar cells working together

Organ

group of tissues working together

Organ system

group of organs working together

Example of tissue

muscle tissue

Example of organ

heart

Example of organ system

digestive system

Organelle that releases energy

mitochondria

Organelle that controls the cell

nucleus

Organelle that makes proteins

ribosomes

Organelle containing chlorophyll

chloroplast

Type of cell division producing identical cells

mitosis

Function of DNA

carries genetic instructions

Smallest level of organisation

cell

Cells that absorb water from soil

root hair cells

Cells that transport water in plants

xylem cells

Cells that transport sugars in plants

phloem cells