Cells

What is Cells?

Building blocks of life
unicellular only one cell
multicellular many types of cells

Facts

All living thing are made up of cells
Smallest working units
==come from preexisting cells through cell division== (细胞分裂)

Prokaryotic and eukaryotes

Nucleus (细胞核)
==EU== true/real
==PRO== original/pre-

organelles and organism

organelles is structure in cell and organism is made up of cells

eukaryotes

Contain organelles surrounded by membranes
Animal and Plant Cells

Structures

Cell Membrane (细胞膜)

1. outer membrane of cell -> separates a cell from surroundings
2. Controls things in and out of cells
3. keeps contents of cell inside.

cell wall -> 细胞壁

Nucleus

1. Contains DNA
2. Directs cell activities
3. Has a nuclear membrane

Chromosomes (染色体)

1. In nucleus
2. Made of DNA
3. Contain instructions for traits and characteristics

Cytoplasm (细胞质)

1. Contains of things like water, solution and organelles.

• Mitochondria (线粒体)

1. Produce energy through chemical reactions
2. Folds create lots of surface area for reactions

Ribosome (核糖体)

1. Contains thousands of them
2. make proteins by translating RNA codes

Cell Wall

1. Only for support, not selecting

Cell Chloroplast (叶绿体)

1. Not all plants have them
2. Contains chlorophyll (叶绿素)
   Large Vacuole(液泡)
3. Store liquid
4. Helps plants maintain shape

Prokaryotic cell

Structure

• Cell Wall
  1. made of ==peptidoglycan==, not cellulose (肽聚糖)
• plasma membrane
• Circular DNA
  1. instead of chromosomes, also called nucleoid
• Plasmid
  1. small circles of DNA
  2. can be exchanged between bacteria
• Cytoplasm
• Ribosomes

Specialised Cells

why: not all cells are identical
same features are found in most cells, most have a particular feature

Cell name	Cell type	Where	function	Features	picture
Red blood cell	Animal	blood	carries oxygen and carbon dioxide	- big surface area so oxygen can get in and out - No nucleus to have more room to carry oxygen
Neuron	Animal	nervous system(nerves, brain, spinal cord)	to carry electronic signals around your body	- Long - Branches at both ends connected to other neurons
Muscle Cell	Animal	muscle tissue	contract and relax	- Packed in bundles to add strength - Can change length for movement
Sperm cell	Animal	Male testis	male sex cell for reproduction	- a long flagellum to swim and find an egg - Has chemicals in its head to break into egg
Egg cell	Animal	Female ovaries	female sex cell for reproduction	- 100 times bigger than other cells because it contains food storage for growing embryo
Ciliated cell (纤毛细胞)	Animal	in airways(tratchea, bronchus)	to clear airways	- tiny cilia (looks like hair) - Cilia move to sweep mucus with trapped dust and bacteria up the throat to be coughed out or swallowed
Root hair cell (根毛细胞)	Plant	in plant root hairs	absorbs mineral and water from soil	- Large surface area to absorb water - Thin cell walls to allow water pass easily - No chloroplasts - Lots of mitochondria
Palisade mesophyll cell (栅栏叶肉细胞)	Plant	top of plant leaves	carry out photosynthesis	- Large surface area to catch as much sunlight as possible - Packed with chloroplasts to maximize photosynthesis - Transparent cell wall and cytoplasm to let light pass through

Groups of organs form organ systems

flowchart LR
	Z(Organelle) --> A
    A(Cell) --> B(Tissue)
    B --> C(Organ)
    C --> D(Organ System)
    D --> E(Organism)

Tissue: composed of cells that are similar and perform a specific function
Organ: a part of the body of an animal or plant that performs a particular job
Organ system- a group of organs with related functions working together to carry out particular body functions