3.2.1.1 Structure of Eukaryotic Cells

nucleus function

• site of DNA replication and transcription, making rRNA

• contains genetic code for each cell

structure of nucleus

1. nuclear envelope,

2. nuclear pores,

3. nucleoplasm,

4. chromosomes,

5. nucleolus

nucleoplasm

granular jelly like material in the nucleus

nuclear envelope

double membrane, contains nuclear pores

nuclear pores

found in nuclear envelope (around 3000), enables molecules to enter and leave

nucleolus

1. smaller sphere inside the nucleus

2. the site of rRNA production

3. makes ribosomes

chromosomes

• found in nucleus,

• protein bound linear DNA

golgi apparatus structure

1. a series of fluid filled flattened and curved sacs making cisternae

2. with vesicles surrounding the edges

golgi apparatus function (7)

1. add carbohydrates to proteins (glycoproteins),

2. produce secretary enzymes,

3. secrete carbohydrates,

4. transport/modify/store lipids

5. form lysosomes,

6. molecules are labelled with their final destination,

7. final products transported to cell surface in Golgi vesicles where they fuse with the membrane and the contents is released

lysosomes structure

1. vesicles/bags of digestive enzymes,

2. bound by single membrane,

3. can have 50 different enzymes

lysosomes function (4)

1. hydrolyse phagocytic cells,

2. break down dead cells (autolysis),

3. release enzymes to outside of cell to destroy material (exocytosis),

4. digest worn out organelle to be reused

mitochondria function

site of aerobic respiration, site of ATP production, DNA codes for enzymes needed in respiration

mitochondria structure

1. oval shaped

2. bound by a double membrane called the envelope

3. inner membrane is folded to form projections called cristae

4. a matrix on the inside containing all the enzymes needed for respiration

5. loop of mitochondria dna

rough endoplasmic reticulum function

synthesise proteins

rough endoplasmic reticulum structure

1. a series of unflattened sacs

2. enclosed by a membrane

3. with ribosomes on the surface

smooth endoplasmic reticulum function

synthesis and store lipids

smooth endoplasmic reticulum structure

system of membrane bound sacs

vacuole function

1. make cell turgid

2. provide support

3. temporary source of sugars and amino acids

4. pigments may colour petals to attract pollinators

vacuole structure

filled with fluid surrounded by single membrane called a atonoplast

what are cisternae?

folded membranes found in RER and SER

xylem tissue specialisation

in plants used to transport water and mineral ions throughout the plant mechanical support

epithelial tissue specialisation

• found in animals,

• consist of sheets of cells line the surface of organs

• often have protective of secretory function

• line the alveoli in lungs and the trachea

name two structures in a eukaryotic cell that cannot be identified using an optical microscope

1. lysosomes

2. ribosomes

3. mitochondrion

4. endoplasmic reticulum

5. cell-surface membrane

cell wall function

provide structural strength and prevent cell bursting

cell wall structure

1. in plants = made of microfibrils of cellulose polysaccharide,

2. in algae = cellulose,

3. in fungi = chitin (a nitrogen containing polysaccharide)

what are plant cell walls made of?

cellulose

what are fungal cell walls made of?

chitin

chloroplast function

site of photosynthesis (light dependent)

chloroplast structure

1. surrounded by a double membrane,

2. contains thylakoids (folded membranes embedded with pigments),

3. fluid filled stroma contains enzymes for photosynthesis in plants

ribosomes function

site of protein synthesis

ribosomes structure

• made of two sub units of protein and rRNA,

• 70s = smaller ribosome found in prokaryotic cells,

• 80s = large ribosome found in eukaryotic cells

tissue definition

collection of similar cells that perform a specific function

explain how the nucleus, rough ER and golgi apparatus are involved in protein synthesis

1. nucleus- the carries instructions for protein synthesis, ribosomal synthesis occurs here rough

2. ER- these are covered in ribosomes, and this is where protein synthesis occurs

3. golgi apparatus- sorts, modifies and packages proteins into vesicles to be transported to the cell membrane

name 2 structures in plant cells that are not present in animal cells

cell wall chloroplasts