Cell Structure, AS AQA

Microscopy!

Resolution is the abiloty to see detail! 

Magnification is the ratio between the actual size of the object and the size of the image. 

Magnification = size of the image/actual size (rearrange for different formulars

Cell ultrastructure

• fine structure of cells visible with an electron microscope
• within cytoplasm fibrous structures composed of protiens which form a cytoskeleton.
• animal and plant cells are EUKARYOTIC as they have a nucleus and organells. 

Rough Endoplasmic Reticulum (RER)

Features

• flat sacs of membrane
• fluid filled
• surface covered in ribosomes

Functions

• protein synthesis
• transport proteins to golgi apparatus. 

Smooth Endoplasmic Reticulum (SER)

Features:

• flat sacs
• fluid filled

Functions:

• make triglycrides (FATS)
• make phospholipids
• Make cholesterol

Golgi apparatus

Features:

• flat sacs piled
• vesicles forming around the edge

Functions:

• modifies protiens by adding carbohydrates
• packages protien
• makes lysosomes

Mitochondria

Features:

• formed of 2 membranes surrounding a fluid filled matrix
• inner memrand folded highly to have greater SA for enzymes of respiration

Functions:

• aerobic respiration

Ribosomes

Features:

• attached to RER or free in cytoplasm
• made of protiens and RNA

Functions:

• assembles amino acids to make proteins

lysosomes

Features:

• single membrane
• fluid filled with enzymes

Functions:

• enzymes destroy worn out parts of the cell
• and digesting food particles.

chloroplasts

features:

• many internal membranes
• large SA for chlorophyll, enzymes of photosynthesis and other pigments. 

Function:

• site of reactions of photosynthesis.

plasma membrane

Function:

• controles entry and exit of materials
• retains cenn content.

nuclear envelope

Features:

• sacs of fluid 
• ribosomes on outer surface
• pores allow substances to pass between cytoplasm and nucleus. 

Function:

• separates cytoplasm and nucleus.

Nucleus:

Function:

• contains genetic information as DNA in chromosomes

Nucleolus:

features: 

• darkly stained area under LM and EM

functions:

• produces ribosomes.

Microfilaments:

features:

• Made of actin -  type of protein. 

function:

• provide mechanical support for cells: apart from the cytoskeleton.

Microtubules:

features:

• made of tubulin - type of protein formes into hollow tubes

funcions:

• part of cytoskeleton
• provides pathways for movement of organelles
• form cillia, flagella (undulipodia) and centrioles
• form spindle to move chromosomes during anaphase

cillia

features:

• extend from cell surface
• made from microtubules
• (9 microtubules and 2 centeral ones)
• surrounded by plasma membrane

functions:

• found in large groups
• move fluid or mucus past cells (trachea)
• move egg in fallopian tube

Undullipodia

features:

•     same as cillia

function:

• found singly
• moves actual cell
• i.e. sperm in animal
• i.e. mosses and ferns in plants. 

Centrioles:

features:

• made of microtubules (9 microtubes and 2 centeral ones)
• not found in flowering plants

function:

• assembles the spindle to move chromosomes
• nuclei division in animal cells

PROKARYOTES:

• do not have a nucleus
• no organelles made of membranes

similar to eukaryotic cells how?

• cytoplasm, ribosomes, cell surface membrane

only found in eukaryotic cells

• nucleus, nucleolus, nuclear envelope, mitochondria, goldi aparatus, chlotoplast, cillia, vacuoles

only found in prokaryotes:

• ring of DNA

some prokaryotes:

• smal rings of DNa known as plasmids, capsual, flagellum (not built of microtubules)