Cell Biology and Histology

Question 1

What reaction forms polymers from monomers?

Answer 1

Dehydration synthesis

Question 2

What is the structure of a nucleotide?

Answer 2

Nucleotides have 3 parts: (1) a base, (2) a phosphate group, and (3) a sugar.

Question 3

What are the bases of DNA and RNA?

Answer 3

DNA = 2 purines: adenine and guanosine; 2 pyrimidines: cytosine and thymine.
In RNA, uracil replaces thymine.

Question 4

What are the sugars in DNA and RNA?

Answer 4

In DNA the sugar is deoxyribose; in RNA the sugar is ribose.

Question 5

What bases pair together in the DNA double helix?

Answer 5

A pairs with T; C pairs with G.

Question 6

What are the four structures of proteins?

Answer 6

Primary structure = the amino acid sequence
Secondary structure = alpha helices and beta pleated sheets
Tertiary structure = the total 3D folded structure of the protein
Quaternary structure = the assembly of different protein subunits to form a functional protein (not all proteins have a quaternary structure)

Question 7

What monosaccharides form maltose?

Answer 7

2 glucose monomers

Question 8

What monosaccharides form lactose?

Answer 8

Glucose and galactose

Question 9

What monosaccharides form sucrose?

Answer 9

Glucose and fructose

Question 10

What is the main component of cell membranes?

Answer 10

Phospholipids

Question 11

What are the different types of membrane proteins for adhesion?

Answer 11

Tight junctions - seal the gaps between epithelial cells.
Adherens junctions - connect actin filaments of one cell with those of the next.
Desmosomes - connect intermediate filaments of one cell with the next.
Hemidesmosomes - anchor intermediate filaments of the cell with the basement membrane.

Question 12

What type of junction allows for communication between cells?

Answer 12

Gap junction

Question 13

What is the difference between channels and carriers?

Answer 13

Channels can only participate in passive transport. Carriers can participate in both passive and active transport. Most use ATP (primary active transport) but some use a concentration gradient as a driving force (secondary active transport).

Question 14

What are the different types of ion channels?

Answer 14

Voltage gated
Ligand gated
Mechanically gated
G-protein coupled

Question 15

What are the different types of carriers?

Answer 15

Uniporters - move one molecule in a single direction
Symporters - move 2 different molecules in the same direction
Antiporters - move 2 molecules in opposite directions

Question 16

What is the role of the endoplasmic reticulum? What is the difference between the rough and smooth ER?

Answer 16

The rough ER is studded with ribosomes –> it is the site of protein synthesis and folding; the smooth ER lacks ribosomes –> its function is drug detoxification, lipid metabolism and calcium release

Question 17

What are the three main cytoskeletal elements?

Answer 17

Microfilaments
Intermediate filaments
Microtubules

Question 18

What is the structure and function of microfilaments?

Answer 18

Microfilaments are made of actin polymers. They maintain cell shape, regulate cell movement (allowing cell crawling) and allow muscle contraction.

Question 19

What is the function of intermediate filaments?

Answer 19

Form desmosomes and hemidesmosomes, which are necessary for cell-cell and cell-matrix interactions respectively.

Question 20

What is the structure and function of microtubules?

Answer 20

Microtubules are compromised of tubulin; which functions in cilia and flagella, forms centrioles to allow mitosis and meiosis, and transports vesicles and organelles in cells.

Question 21

What are the 4 types of tissue?

Answer 21

Epithelial
Connective
Muscle
Nervous

Question 22

Where is epithelial tissue found?

Answer 22

It lines the body surface and body cavities, forming the external and internal linings of many organs.

Question 23

What are the different types of glands? How are they different?

Answer 23

Exocrine glands have ducts through which the secretory products are delivered onto an epithelial surface. Endocrine glands have no ducts, and the secretory products are released into the bloodstream or lymphatic vessels directly.

Question 24

What is connective composed of?

Answer 24

Ground substance: glycosaminoglycans, proteoglycans, glycoproteins
Fibres: elastic and collagen fibres
Cells: such as fibroblasts, adipose cells

Question 25

What are the different types of cartilage? What are their characteristics?

Answer 25

There are three types of cartilage: (1) hyaline, (2) elastic and (3) fibrocartilage.
Hyaline = type II collagen with chondrocytes arranged in groups; found in joints, trachea and bronchi, nose and larynx.
Elastic = type II collagen with elastic fibres; found in the ear and epiglottis.
Fibrocartilage = type I collagen with chondrocyte arranged in parallel rows; found in IV discs and the pubic symphysis.

Question 26

What is the function of hyaline cartilage? Explain.

Answer 26

Hyaline cartilage absorbs shock in joints, and allows smooth articulation of joints by limiting friction. The cartilage matrix possesses abundant aggrecans, which are negatively charged and so attract Na+ ions –> in turn, this attracts water molecules –> the cartilage has a high water content, which allows it to resist compression.

Question 27

What are the layers of skin?

Answer 27

Epidermis: has 5 layers -
Stratum basale: sits on the basement membrane, contains cells undergoing cell division that migrate upwards.
Stratum spinosum: cells have cytoplasmic extensions that resemble spines.
Stratum granulosum: cells have granules that contain lipid. these are exocytosed and prevent fluid moving in either direction through this layer - makes the epidermis waterproof.
Stratum lucidum - a transparent layer of cells.
Stratum corneum - this is the most superficial layer of skin; the cells have died and are filled with keratin filaments. these cells are sloughed off.
Dermis - is a connective tissue layer than lies beneath the epidermis.
Has a superficial papillary layer and a deep reticular layer.

Question 28

What are the functions of skin?

Answer 28

Form a cover for the body
Protect against dehydration
Protect against bacteria
Absorb UV radiation for vitamin D production
Receive information from the environment - e.g. touch, temperature
Regulate temperature
Sweat excretion
Produce melanin

Question 29

What are the cell types in the epidermis and what are their roles?

Answer 29

Keratinocytes
Langerhans cells: these are antigen-presenting cells
Melanocytes: produce melanin to protect against UV radiation
Merkel cells: mechanoreceptors for sensing touch