Topic 1.2 Cell Structure

Question 1

Prokaryote Structure

Answer 1

Cytoplasm – internal fluid component of the cell
Nucleoid – region of the cytoplasm where the DNA is located (DNA strand is circular and called a genophore)
Plasmids – autonomous circular DNA molecules that may be transferred between bacteria (horizontal gene transfer)
Ribosomes – complexes of RNA and protein that are responsible for polypeptide synthesis (prokaryote ribosome = 70S)
Cell membrane – Semi-permeable and selective barrier surrounding the cell
Cell wall – rigid outer covering made of peptidoglycan; maintains shape and prevents bursting (lysis)
Slime capsule – a thick polysaccharide layer used for protection against dessication (drying out) and phagocytosis
Flagella – Long, slender projections containing a motor protein that enables movement (singular: flagellum)
Pili – Hair-like extensions that enable adherence to surfaces (attachment pili) or mediate bacterial conjugation (sex pili)

Question 2

KEY Animal Eukaryotic Structure

Answer 2

Nucleus – shown as double membrane structure with pores
Mitochondria – double membrane with inner one folded into cristae ; no larger than half the nucleus in size
Golgi apparatus – shown as a series of enclosed sacs (cisternae) with vesicles leading to and from
Endoplasmic reticulum – interconnected membranes shown as bare (smooth ER) and studded (rough ER)
Ribosomes – labelled as 80S
Cytosol – internal fluid labelled as cytosol (‘cytoplasm’ is all internal contents minus the nucleus)

Question 3

KEY Plant Eukaryotic Structure

Answer 3

Vacuole – large and occupying majority of central space (surrounded by tonoplast)
Chloroplasts – double membrane with internal stacks of membrane discs (only present in photosynthetic tissue)
Cell wall – labelled as being composed of cellulose ; thicker than cell membrane
Shape – brick-like shape with rounded corners