Organelles

Question 1

The Nucleus

Answer 1

Contains the cell’s genetic information and controls the activity of the cell

Genome is here and only seen during cell division when chromatin coils and condenses into thick chromosomes

Double layer membrane with pores for the export of mRNA and import of proteins

Nucleolus visible in interphase and involved in the production of rRNA

Shape maintained by protein skeleton

Question 2

Endoplasmic reticulum

Answer 2

System of membranous tubules and sacs branching throughout the cytoplasm providing an intracellular highway for molecules movement and modification

Highly folded membrane continuous with the outer nuclear envelope

Rough ER has ribosomes and processes proteins and amino acid sequences directed into ER lumen

Proteins chemically modified (folded)

Smooth ER has few ribosomes and embedded transmembrane enzymes involved in the production and processing of lipids and carbohydrates

Sequesters calcium for muscle contraction

Question 3

Golgi apparatus

Answer 3

System of membrane sacs (cisternae) associated with vesicles working closely with ER

Proteins modified and commonly have sugars added

Materials packaged into vesicles which pinch off and move to the membrane for exocytosis

Question 4

Lysosomes and Endosomes

Answer 4

Vesicles containing digestive enzymes produced from ER/Golgi which fuse to form endosomes

Membrane-bound vesicles of digestive hydrolytic enzymes

Digest incoming material or internal matter

Common in animals, fungi and protists

Specialized membrane with transporters to export digestion products and pumps protons

Question 5

Mitochondria

Answer 5

Energy production in aerobic respiration

Two membranes with the inner membrane having extensive invaginations (cristae) to increase SA = forming an inner matrix

Embedded with metabolic proteins (ATP synthase) providing ATP for respiration

Own genome has a set of circular DNA = encodes several genes for metabolism
= ENDOSYMBIONT THEORY

Question 6

Plastids/Chloroplasts

Answer 6

Double membrane with inner space (stroma) with stacks of thylakoids arranged into coil-like stacks called grana (linked by thylakoids)

Contains chlorophyll with protein photoreceptors on the thylakoid membrane being the site of photosynthesis

Own genome has a set of circular DNA = encodes several genes for metabolism
= ENDOSYMBIONT THEORY

Question 7

Vacuoles

Answer 7

Storage area for water, chemicals and some poisons/toxins

Bounded by a tonoplast membrane with protein pumps

Plant cells provide a high turgor pressure = pushing against cell wall

Animal cells have smaller vacuoles involved in food digestion/contraction

Question 8

Centrioles

Answer 8

involved in nuclear division and creating the spindle network

Question 9

Ribosomes

Answer 9

Dense staining granules as the site of protein synthesis

Question 10

Cytoskeleton

Answer 10

Proteinaceous microtubules, microfilaments and intermediate filaments providing cell framework and motility.