Eukaryotic Cell Diversity - lecture 5

Question 1

what are embryonic stem cells?

Answer 1

cells produced at around the 50-cell stage

Question 2

totipotent stem cell meaning?

Answer 2

have the ability to differentiate into any type of cell

Question 3

summarise the steps of gene expression

Answer 3

• coding and noncoding regions of DNA are transcribed into mRNA
• introns are removed during initial mRNA processing
• remaining exons are then spliced together, and the spliced mRNA molecule is prepared to export out of the nucleus through the addition of an endcap and a polyA tail
• once in the cytoplasm, the mRNA can be used to construct a protein

Question 4

what are the 4 major classes of cell surface receptors?

Answer 4

• G protein coupled receptors
• Tyrosine kinase-linked receptors
• ion channel receptors
• receptors with intrinsic enzymatic activity

Question 5

what is apoptosis?

Answer 5

• morphologically distinct cell death - programmed cell death
• roles in embryogenesis, tissue homeostasis, damage limitation, control and functioning of the immune system

Question 6

what are the 2 main gene families involved in apoptosis

Answer 6

Bcl-2 family - regulation

caspase family - execution

Question 7

what are the characteristics of apoptosis?

Answer 7

(1)
- mild convolution
- chromatin compaction and margination
- condensation of cytoplasm

(2)

• breakup of nuclear envelope
• nuclear fragmentation
• blebbing
• cell fragmentation

(3)
- phagocytosis

Question 8

consequences of too-little apoptosis?

Answer 8

• cancer
• autoimmune diseases
• prolonged viral infection

Question 9

consequences of too much apoptosis?

Answer 9

• neurodegenerative diseases
• autoimmune diseases where cells are attacked by immune cells
• additional tissue damage following trauma
• progression of AIDS

Question 10

how does apoptosis become unregulated?

Answer 10

• genes controlling apoptosis become damaged or aberrantly expressed
• inappropriate triggering of apoptosis
• interference by exogenous genes - viral, bacterial, parasitic

Question 11

what are the 4 cell types of the epithelia?

Answer 11

• epithelial cells: form sheets that cover the inner and outer body surfaces
• absorptive cells have microvilli

Question 12

what are the 4 main types of intestinal cells?

Answer 12

• absorptive cells
• goblet cells; secrete mucus
• paneth cells; secrete growth factors and antibacterial substances
• enteroendocrine cells; secrete peptide hormones and serotonin into gut wall

Question 13

what are rod cells?

Answer 13

• specialised sensory cells in the retina
• layers of disks contain the light sensitive pigment called rhodopsin
• light evokes an electrical signal that is transmitted to the brain

Question 14

what are erythrocytes?

Answer 14

• highly specialised cells for transportation of oxygen

- major protein component is haemoglobin

Question 15

what is connective tissue?

Answer 15

• fills the spaces between epithelial sheets and tubes

- fibroblast is embedded in the extracellular matrix secreted by itself and neighbouring cells

Question 16

what are YAP and TAZ?

Answer 16

transcription regulators that move to the nucleus in response to tension developed in the actin-myosin bundles in the cytoplasm

Question 17

what are the different types of muscle cells?

Answer 17

• cardiac muscle; located in the wall of the heart. adjacent cells connected by electrical conducting junctions to ensure synchronous contraction
• skeletal muscle- striated muscle fibres are made from multinucleated cells. control voluntary movement of joints
• smooth muscle- thin elongated cells, control involuntary movements of digestive tract, arteries, visceral organs