Eukaryotic Cell Diversity - lecture 5 Flashcards
what are embryonic stem cells?
cells produced at around the 50-cell stage
totipotent stem cell meaning?
have the ability to differentiate into any type of cell
summarise the steps of gene expression
- 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
what are the 4 major classes of cell surface receptors?
- G protein coupled receptors
- Tyrosine kinase-linked receptors
- ion channel receptors
- receptors with intrinsic enzymatic activity
what is apoptosis?
- morphologically distinct cell death - programmed cell death
- roles in embryogenesis, tissue homeostasis, damage limitation, control and functioning of the immune system
what are the 2 main gene families involved in apoptosis
Bcl-2 family - regulation
caspase family - execution
what are the characteristics of apoptosis?
(1)
- mild convolution
- chromatin compaction and margination
- condensation of cytoplasm
(2)
- breakup of nuclear envelope
- nuclear fragmentation
- blebbing
- cell fragmentation
(3)
- phagocytosis
consequences of too-little apoptosis?
- cancer
- autoimmune diseases
- prolonged viral infection
consequences of too much apoptosis?
- neurodegenerative diseases
- autoimmune diseases where cells are attacked by immune cells
- additional tissue damage following trauma
- progression of AIDS
how does apoptosis become unregulated?
- genes controlling apoptosis become damaged or aberrantly expressed
- inappropriate triggering of apoptosis
- interference by exogenous genes - viral, bacterial, parasitic
what are the 4 cell types of the epithelia?
- epithelial cells: form sheets that cover the inner and outer body surfaces
- absorptive cells have microvilli
what are the 4 main types of intestinal cells?
- absorptive cells
- goblet cells; secrete mucus
- paneth cells; secrete growth factors and antibacterial substances
- enteroendocrine cells; secrete peptide hormones and serotonin into gut wall
what are rod cells?
- 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
what are erythrocytes?
- highly specialised cells for transportation of oxygen
- major protein component is haemoglobin
what is connective tissue?
- fills the spaces between epithelial sheets and tubes
- fibroblast is embedded in the extracellular matrix secreted by itself and neighbouring cells
what are YAP and TAZ?
transcription regulators that move to the nucleus in response to tension developed in the actin-myosin bundles in the cytoplasm
what are the different types of muscle cells?
- 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
