Eukaryote Structures

Give the structure of the nucleus (3)

• Double membrane (nuclear envelope)

• Nuclear pores

• Nuclear envelope

What is the function of the nucleus (2)

• Controls activities of the cell

• Contains genetic material

What is the nucleolus

A dense area of chromatin

What does the nucleolus do

Produces ribosomes

What is the role of the cell surface membrane (3)

• Controls exchange between cell and surrounding environment

• Cell receptors for recognition

• Contains fluid for endo/exocytosis

How big is the cell surface membrane

7nm

What is the cell membrane made of (2)

• Phospholipid bilayer

• Glycoprotein complex

What is the role of protein the rough endoplasmic reticulum (2)

• Protein synthesis

• Transport

Give the structure of the rough endoplasmic reticulum (2)

• Flattened sacs (cisternae)

• Studded with ribosomes

Where is the endoplasmic reticulum found and why (2)

• Continuous with the outer membrane of the nucleus

• Close to DNA

Role of smooth endoplasmic reticulum

• Lipid synthesis

• Transport

What’s the difference in structure between smooth and rough endoplasmic reticulum

There are no ribsomes on the smooth endoplasmic reticulum

Whats the role of the golgi body (3)

• Collects and processes proteins

• Transports molecules in secretory vesicles

• Lysosome formation

Give the faces of the golgi body (2)

• Cis face

• Trans face

What is the role of the mitochodria and how (2+3)

• Site of respiration

• Synthesis of lipids

• Produces ATP (adenosine triphosphate)

• ATP broken down to ADP (adenosine diphosphate) to release energy in hydrolysis

• ADP can be stored and converted back to ATP

Give the size and shape of the mitochondria (2+1)

• 3-10μm long

• 0.5-1μm wide

• Rod shaped

Describe the structure of mitochondria and what it contains (2+2)

• Double membrane

• Inner membrane folded to form cristae

• Ribosomes (70S)

• Circular DNA

Explain the role of the matrix

• Where respiration reaction takes place (+cristae)

• Contains enzymes in solution

Give the role of a ribosome and what it is made of

• Allows interaction for protein synthesis

• Made protein and rRNA

Describe the structure and size of a ribsosome (2+1)

• Two subunits

• Groove for mRNA attachment

• 25nm

Describe the structure and size of a lysosome (2+1)

• Little, spherical sacs

• Single membrane bound vesicle (prevents self digestion)

• 0.1-0.5μm

Explain the role of the lysosome (2)

• Breaks down unneeded substances

• Self digestion (enzymes released into cytoplasm)

Optimal condition for lysosome and why (2)

• Acidic conditions

• Optimal pH for hydrolytic (digestive) enzymes

Give the role of centrioles (3)

• Cell division

• Separates chromosomes to opposite ends of cell (moved by spindle fibres)

• Produces cilia

Give the arrangement of centrioles (2)

• 9+2 arrangement

• At right angles to each other (in pairs called centrosomes) outside nucleus (till ready to split)

What is the role of the microtubules (3)

• Gives cell structure (cytoskeleton)

• Moves stuff around in cell

• Spindle fibres separate chromatids/chromosomes

What are microtubules made of

Tubulin

What do microtubules make up (4)

• Centrioles (general)

• Specialised structures

  • Flagella

  • Cilia

• Spindle fibres

Give the size and structure of microtubules

• 25nm (diameter)

• Long, rigid, hollow tubes

Give the role of the cilia

Movement (eg gas exchange moves mucus in airways)

How long are cilia

10μm

Role of microvilli

Increases surface area for absorption at brush border

How big are microvilli

1μm

How big are chloroplasts

4-10μm

Describe the structure of a chloroplast (7)

• Double membrane

• Inner membrane folded into stacks called grana (granum)

• Grana made of thylakoids studded with chlorophyll

• Thylakoid centre is the lumen

• Grana linked with lamelle

• Intermembrane space is fluid called stroma

• Contains 70S ribosomes

What is the tonoplast

A single membrane that surrounds the vacuole/cell sap

What is the role of the tonoplast

Controls exchange between vacuole and cytosplasm

What is the role of the cell wall (2)

• Provides structure and support for the cell

• Prevents bursting due to water entering via osmosis (turgid pressure against membrane)

Describe the structure of the cell wall

Cellulose microfibrils held together by hemicellulose

What is the role of the vacuole (3)

• Contains cell sap

• Maintains water potential of cell

• Regulates turgid pressure

What does the cell sap contain (3)

• Salts

• Sugars

• Water

What is a starch grain

Storage area

What is the plasmodesmata

• Part of symplasmic pathway

• Inorganic ions to pass through between cells

• Cytoplasmic connection through cell wall