Cell Biology

Question 1

Cells can be divided into what three main areas?

Answer 1

The nucleus
The cytoplasm
The Plasma membrane

Question 2

What is a composite cell?

Answer 2

Show all the features a cell could theoretically have

Question 3

What are the general features of the nucleus?

Answer 3

Location of DNA
Controls cellular activity
Separated from the cytoplasm by a double-layered, porous membrane termed the nuclear envelope

Question 4

What is encoded in DNA?

Answer 4

The genetic blueprint which determines the majority of human traits

Question 5

What are karyographs?

Answer 5

Photographs of chromosomes arranged in pairs by size prepared to determine an individuals karyotype.

Question 6

What is the name given to genetic defect testing before birth?

Answer 6

Amniocentesis

Question 7

Clinical features of down syndrome

Answer 7

single transverse palmar crease, flattened facial features, large gap between first and second toe, enlargement of the tongue, arterial defects (holes in the heart)

Question 8

Summarise patau syndrome

Answer 8

• Caused by trisomy 13
• Has serious physical defects:
  incomplete brain development, cleft palete, missing eyes

Question 9

What is the ER?

Answer 9

A system of interconnected flattened membranes

Question 10

The rough ER is the site of what?

Answer 10

Protein synthesis

Question 11

The smooth ER is the site of what?

Answer 11

Lipid synthesis

Question 12

The cytosol is a mixture of what?

Answer 12

water, salt, sugar, amino acids and growth factors

Question 13

The nucleus, nucleolus and origin of ribosomes

Answer 13

The nucleolus synthesises rRNA which leaves the nucleus via nuclear pores before being assembled into ribosomes within the RER

Question 14

What are the 3 major roles of the Golgi body?

Answer 14

1) Refines crude proteins from the RER by adding sugar residues = glycosylation
2) It packages material for export outside of the cell
3) It packages lysosomes (sacs of enzymes)

Question 15

Summarise lysosomes

Answer 15

• Sacs of enzymes which function as the cells digestive apparatus
• Lysosomes bud off the Golgi
  apparatus and contain enzymes which
  are used to digest material within
  cells
• For example when a leukocyte (white
  blood cell) such as a neutrophil traps
  a bacterium by phagocytosis the lysosomes are responsible for discharging their enzymes to kill
  and break down the pathogen. This
  process is referred to as intracellular
  digestion

Question 16

Mitochondria

Answer 16

Responsible for cellular respiration
Smooth outer membrane, highly folded inner membrane
Inner folds = cristae
cristae = location of respiratory enzymes
Mitochondria contain their own
complement of DNA (mitochondrial
DNA) and can replicate independently
of the cell

Question 17

The plasma membrane

Answer 17

The bulk of the membrane has a phospholipid bilayer
Within the layer there are a variety of structural and functional proteins e.g. receptors and channel proteins
Groups of sugar molecules on the outer surface of the cell membrane form the glycocalyx, which allows cells to recognise eachother and non-self materials like bacteria and viruses

Question 18

What are the four major functions of the plasma membrane?

Answer 18

1) Holds the cell together as a discrete intact unit
2) Membrane transport - regulates the movement in and out of the cell
3) Plays an important role in cell signalling via receptors, plays an important role in cell recognition

Question 19

What are microvilli?

Answer 19

Non-motile extensions
Finger-like projections which increase surface area for the absorption of nutrients e.g. in the gastrointestinal tract

Question 20

What are cilia and flagella?

Answer 20

Motile projections
Cilia- hair-like projections which move material such as mucus
Flagella - only found in
spermatozoa where they function to
propel the spermatozoa by rhythmic
whip-like movements