Eukaryotic Cell Structure

Question 1

Describe the strucuture of the following:
-Nucleus
-Mitochondria
-Chloroplasts
-Rough and smooth endoplasmic reticulum
-Golgi apparatus
-Lysozomes
-Ribosomes
-Cell Wall
-Vacuole

Answer 1

STRUCTURE
=Nucleus:
-Nuclear envelope (Double membrane) surrounds the nucleus, perforated with nuclear pores that allow the passage of larger molecules, such as mRNA.
-Nucleoplasm is the granular, jelly-like material that makes up the bulk of the nucleus.
-Chromosomes are protein-bound DNA coils within the nucleus.
-Nucleolus is a small region that manufactures rRNA and assembles ribosomes.

=Mitochondria:
-Double membrane with inner foldings known as cristae.
-Matrix makes up the remainder of the mitochondrion and contains vital enzymes involved in respiration.

=Chloroplasts:
-Envelope surrounds the organelle and is highly selective in what it allows to enter and leave the chloroplast.
-Grana are stacks made up of thylakoids which contain chlorophyll.

=Rough and smooth endoplasmic reticulum
-Rough endoplasmic reticulum has ribosomes on its surface made up of sheet-like membranes and flattened sacs called cisternae.
-Smooth endoplasmic reticulum is more tubular in appearance.

=Golgi Apparatus
-Made up of cisternae and vesicles.

=Lysosomes
-Vesicles containing enzymes such as proteases and lipases.
-Contains lysozomes.

=Ribosomes
-Two sub units; one large and one small.
-Small cytoplasmic granukes found in all cells.

=Cell Wall
-Contain polysaccharides such as cellulose.
-Thin layer called the middle lamella, which marks the boundary between adjacent cell walls.

=Vacuole
-Fluid filled sac bounded by a single membrane
-Single membrane surrounding it is called a tonoplast

Question 2

Describe the function of the following:
-Nucleus
-Mitochondria
-Chloroplasts
-Rough and smooth endoplasmic reticulum
-Golgi apparatus
-Lysozomes
-Ribosomes
-Cell Wall
-Vacuole

Answer 2

=Nucleus
-Act as the control centre of the cell through the production of mRNA and tRNA
-Retain the genetic material of the cell in the form of DNA and chromosomes
-Manufacture rRNA and ribosomes.

=Mitochondria
-Site of aerobic stages of respiration
-Responsible for ATP production

=Chloroplasts
-Carry out photosynthesis
-Stroma fluid contains enzymes needed to make sugars in stage two photosynthesis
-DNA and ribosomes quickly and easily manufacture necessary proteins for photosynthesis

=Rough and Smooth Endoplasmic Reticulum
-ROUGH: Synthesises proteins and glycoproteins, transports materials throughout the cell.
-SMOOTH: Synthesises and stores lipids and carbohydrates.

=Golgi Apparatus
-Forming glycoproteins
-Producing secretory enzymes
-Transport, modify and store lipids
-Form lysosomes

=Lysosomes
-Hydrolyse material ingested by phagocytic cells
-Release enzymes to be outside of the cell
-Digest worn out organelles so that the useful chemicals can be re-used
-Completely break down cells after they have died

=Ribosomes
-Synthesize proteins

=Cell Wall
-Provide mechanical strength in order to prevent the cell bursting under osmotic pressure
-Allows water to pass along it and contribute to the movement of water through the plant

=Vacuole
-Makes cells turgid
-Stores sugars and amino acids temporarily
-Can attact pollinating insects