Intro to Cells Flashcards
Name 4 features that ALL cells posses
- Cell membrane
- DNA
- Cytoplasm
- Ribosomes
What are the differences between prokaryotic and eukaryotic cells?
- Prokaryotic cells: Small, relatively simple internal structures, no membrane-bound organelles, no true nucleus
- Eukaryotic cells: Larger, more complex, membrane-bound organelles, true nucleus, found in higher animals and plants
Where is the nucleolus located and what does it produce?
In the nucleus, produces ribosomes
Where are microtubules produced?
The centrosome - microtubule organising centre (MTOC)
Where does protein synthesis occur?
Ribosomes
What are the roles of the cytoskeleton?
- Helps to maintain cell shape
- Involved in cell motility
What is the plasma membrane?
- A semi-permeable barrier between the cytoplasm and external environment
- Retains most organically produced chemicals inside the cell
- Allows a few molecules across: diffusion, facilitated diffusion, osmosis, active transport
- Communication: receptors on cell surface
What is the fluid mosaic model?
- The cell membrane is a lipid bilayer: described as a fluid mosaic model
- Made up of phospholipids: polar (hydrophilic) heads and 2 non-polar (hydrophobic) tails
- Cholesterol embedded in the bilayer - provides membrane integrity (prevents lysis)
- Proteins: gateways that allow certain molecules into and out of the cell
What are some examples of cell membrane pathologies?
Haemoglobinopathies:
Sickle cell anaemia
Thalassaemia
Which type of cells contain a nucleus?
Eukaryotic cells
Describe the structure of the nuclear envelope
Double membrane, allows RNA and other chemicals to pass but NOT DNA
Where are ribosomes constructed?
In the nucleolus
How many chromosomes does a human have?
46
How is DNA organised within the nucleus of a eukaryotic cell?
It is condensed into chromatin
DNA wrapped around proteins called histones
Where does transcription of proteins occur?
In the nucleus
Where does translation of proteins occur?
Ribosomes
Describe the structure of ribosomes
- Present in eukaryotic and prokaryotic cells (larger in eukaryotes)
- Structure = a small and a larger subunit
- Role is to facilitate protein translation
Which organelle is described as a a protein factory of the cell?
Ribosomes
Give an example of a ribosomopathy
Treacher Collins syndrome (TCS) - results in abnormal craniofacial development
What is the endoplasmic reticulum?
- Mesh of interconnected cell membranes
- Involved in protein synthesis and transport
What is the role of the rough endoplasmic reticulum? (RER)
- Protein modification and production
- The rough endoplasmic reticulum connects to the nuclear envelope; mRNA is converted to peptides and passed on to the rough endoplasmic reticulum
Which disorders does endoplasmic reticulum dysfunction play a role in?
- Plays a role in numerous degenerative disorders: Alzheimer’s, Parkinson’s, Epilepsy
What is ER dysfunction assoiated with?
Ageing
What is the function of the smooth endoplasmic reticulum?
Manufacture of lipids
What important role does the smooth endoplasmic reticulum play in liver cells?
Detoxifies organic chemicals converting them into safer water-soluble products
What is the role of the Golgi apparatus?
- Post-translational modification
- Stores proteins
- Packages proteins
After proteins are correctly folded in the rough endoplasmic reticulum, where are they transported to?
The Golgi Apparatus
How do proteins leave the golgi apparatus?
In vesicles and are transported to required site or exported
What are some examples of Golgi-related diseases?
- Hypomyelinating disorders e.g. cataracts
2. Muscular dystrophy
What is a vacuole?
- Single-membrane organelles
- Used as storage areas
- Formed by fusion of numerous vesicles
What are vesicles?
- Function in transport within and to the outside of the cell
What are lysosomes?
- Large vesicles formed by the Golgi apparatus
- Contain hydrolytic enzymes capable of destroying the cell
- Lysosome contents function in the breakdown of extracellular materials
What is the role of mitochondria?
Powerhouse of the cell
Function as sites of energy release and ATP formation
What is mtDNA?
maternal DNA - contained within mitochondria
Which organelles are bound by 2 membranes?
Mitochondria and nucleus
Describe the membranes of the mitochondria
- Double membrane
- Outer membrane is smooth and ‘sieve’-like
- Inner membrane folded into cristae - surfaces on which ATP is generated
Which surface of the mitochondria is ATP generated?
- Inner membrane folds called cristae
What can mutations in mtDNA be associated with?
Alzheimer’s disease, parkinson’s disease, huntington disease, diabetes, cardiovascular disease, stroke, autoimmune disease, cancer
What is the cytoplasm?
The material between the cell membrane and nuclear envelope
Describe the cytoplasm
Not static - facilitates transport of material around the cell (cytoplasmic streaming)
What are the roles of the cytoskeleton?
- Maintain shape of the cell
- Anchors organelles
- Moves cell
- Controls internal movement of organelles
Which protein filaments is the cytoskeleton composed of?
- Microtubules
- Actin filaments
- Intermediate filaments
What are the stages of mitosis?
4 stages: prophase, metaphase, anaphase, telophase
