Introduction to Cells Flashcards
What are cells?
The building blocks of complex life
Fill in the gaps
Cell —-> —-> —-> Organ System
Cell —-> Tissue —-> Organ —-> Organ System
What are cells vital for?
All of life’s processes
What can disturbances in cell function underpin?
-Many disease processes, including those affecting the oral cavity
Cells vary in shape and size resulting in what?
Differences in functionality i.e. nerves, epithelial, sperm etc
What common features do ALL cells have?
-Cell membrane
-DNA
-Cytoplasm
-Ribosomes
Describe the size of prokaryotic cells?
small
What is the internal structure of prokaryotic cells like?
Relatively small internal structure, no internal membrane bound structures or organelles
What organisms are made up of prokaryotic cells
Bacteria and their close relatives
What is the nucleus of prokaryotic cells like?
No true nucleus
Size of eukaryotic cells?
Larger
Internal structure of eukaryotic cells?
More complex
Where are eukaryotic cells found
Higher animals and plants
Do eukaryotic cells have a nucleus?
Yes
What structure is this?
Cell (plasma) membrane
Cell membrane function;
What is the cell membrane?
A semi-permeable barrier between cytoplasm and external environment
Cell membrane function;
What does it retain?
Most organically produced chemicals inside the cell
Cell membrane function;
Through what processes does the cell membrane allow a few molecules across it?
-Diffusion
-Facilitated Diffusion
-Osmosis
-Active Transport
Cell membrane function;
How does it allow communication
Through receptors on the cell surface
Cell membrane function;
How does it allow communication
Through receptors on the cell surface
Cell membrane structure;
What is the structure of the cell membrane?
Lipid bilayer (fluid mosaic) model
Cell membrane structure;
What is the structure of the cell membrane?
Lipid bilayer (fluid mosaic) model
The cell membrane structure;
Most common molecule in the cell membrane?
Phospholipid;
-Composed of hydrophilic/ polar head and two hydrophobic/ non-polar tails
Cell membrane structure?
Where is cholesterol in the cell membrane and what is its function there?
-Embedded in inner area of bilayer
-Provides membrane integrity, prevents lysis
Cell membrane Structure;
What is the function of the proteins in the cell membrane?
Gateways that allow certain molecules in and out of the cell
Typical cell membrane diagram;
Name a cell membrane pathology and two diseases that result from this pathology
Haemoglobin pathologies
-Sickle cell anaemia
-Thalassemia
How does one develop sickle cell anaemia and Thalassemia
Both hereditary
What are sickle cell anaemia and Thalassemia characterised by?
Defects in haemoglobin
In haemoglobin patties What can lead to a decrease in red blood cell’s life span?
-Alterations in organisation of lipid bilayer
-Red blood cells are also not replaced as effectively
What is this structure?
NUCLEUS
In what cells does the nucleus occur?
ONLY in eukaryotic cells
What is the nucleus the location of?
Most of the different types of nucleic acid
DNA Is largely restricted to where?
The nucleus
Where is RNA formed, how is it formed and where does it move to?
-RNA is formed in the nucleus
-By coding off the DNA bases
-Moves out into the cytoplasm
What is the nuclear envelope and what does it do?
A double membrane structure- allows RNA and other chemicals to pass, BUT NOT DNA
What is the NUCLEOLUS?
Area where ribosomes are constructed
What is the nucleus the site of?
Transcription
Give a brief summary of protein secretion?
DNA transcription to RNA - Transport to cytoplasm - Translation to protein - Protein Secretion
What structure Is this?
What structure Is this?
What structure Is this?
Ribosomes
In what cells ribosomes occur?
Prokaryotic and eukaryotic cells
What is a difference between the ribosomes of prokaryotic and eukaryotic cells?
Eukaryotic ribosomes are slightly larger than prokaryotic ribosomes
What is the structure of ribosomes like?
Eukaryotic ribosomes are slightly larger than prokaryotic ribosomes
What is the structure of ribosomes like?
A small and a larger subunit
Main role of ribosomes?
Facilitate protein translation
What does the structure of a ribosome in nature relate to?
Its function
Describe Ribosome pathologies (ribosomepathies)
-Originally thought to be fatal
-Now number of pathologies due to defects in ribosome synthesis
-Rare
Name a disease caused by ribosomopathies and what does it result in?
Treacher Collins Syndrome (TCS)
results in- abnormal craniofacial development
What are these structures?
Endoplasmic Reticulum
What is the endoplasmic reticulum (ER)
-Mesh of interconnected membranes
-Involved in protein synthesis and transport
What is the endoplasmic reticulum (ER)
-Mesh of interconnected membranes
-Involved in protein synthesis and transport
What does the ROUGH endoplasmic reticulum connect?
Rough endoplasmic reticulum connects to the nuclear envelope: messenger RNA (blueprint for proteins) converted to peptide and passed on to rough ER
What is the key function of the rough endoplasmic reticulum?
Protein modification and production
Give examples of what proteins the RER acts on
Lysosomal enzymes
Secreted proteins
Integral membrane proteins
Give examples of how RER modifies proteins.
-Correct folding – important for function
-Appropriately ‘tagged’ for distribution throughout cell
-Post-translational modifications – structure and function
What is the predominant function of the smooth endoplasmic reticulum?
Manufacture of lipids
Where is the Smooth ER more abundant
in some cells than others and have specialised functions;
Liver – glycogen broken down to glucose
Adrenal cortex – steroid hormone production
Muscle – Ca2+ storage – sarcoplasmic reticulum.
Contraction of muscle cells is triggered
by the orderly release of calcium ions.
Why is the smooth ER known as the detox stop, give an example?
-Smooth ER also plays a large part in detoxifying a number of organic chemicals converting them to safer water-soluble products.
-In the liver (hepatocytes) Smooth ER can double its surface area within a
few days, returning to its normal size when the assault has subsided.
What does endoplasmic reticulum dysfunction result in?
Defective folding and processing of proteins
-ER dysfunction plays a role in what type of disorders, give examples.
- What else is ER dysfunction associated with?
- Numerous Degenerative Disorders such as;
- Alzheimer’s
- Parkinson’s
-Epilepsy
-Also associated with ageing
What structure is this?
Golgi apparatus
Correctly folded proteins will do move where?
Drom ER to Golgi Apparatus via vesicles
Proteins move from ER to Golgi via what?
Vesicles
Give 3 functions of Golgi apparatus
-Further modifies proteins (post-translational)
-Stores Proteins
-Packages Proteins
How do proteins leave Golgi apparatus and where are they transported to?
Leave Golgi in vesicles and are transported to required site or are exported
Give 3 different types of Golgi-related impairments
-Impaired trafficking of proteins through Golgi
-Impairments in post-translational modification capacity
-Functionality loss due to mutations in proteins that make up Golgi
Give a disease which is a consequence of Impaired trafficking of proteins through Golgi
Defect in trafficking of protein important in making myelin (insulates nerve fibres and promotes signalling) causes hypomyelinating disorders (e.g. cataract)
Give a disease which is a result of Impairments in post-translational modification capacity
Defective glycosylation disorders (glycoprotein and glycolipids)
Wide spectrum of pathologies that effect multiple organs
Give a disease which is a result of Functionality lost due to mutations in proteins that make up Golgi
Muscular dystrophy
What structures are these?
Vacuoles, Vesicles and Lysosomes
What are vacuoles?
Where are they located?
What are they used as?
How are they formed?
-Single membraned organelles
-Essentially part of the ‘outside’, located within the cell
-Used as storage areas
-Formed by fusion of numerous vesicles
What is the size of vesicles like compared to vacuoles?
What is their function?
Much smaller than vacuoles
Function in transport, within and to the outside of the cell
What are Lysosomes?
What do they contain?
What is their function/ their contents function?
-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 structure is this?
Mitochondria
What do mitochondria contain?
Their own DNA (mDNA) - Maternal
What are mitochondria thought to represent?
Bacteria-like organisms incorporated into eukaryotic cells over 700 million organisms
What do mitochondria function as?
Sites of energy release (following glycolysis In the cytoplasm) and ATP formation; the POWERHOUSE of the cell
How are mitochondria bounded?
By two membranes
The mitochondria is bounded by two membranes;
-What is the outer membrane like?
-What is the inner membrane like?
-Outer membrane is smooth and ‘sieve’ like
-Inner membrane is folded into CRISTAE- surfaces on which ATP is generated (highly selective)
Structure of mitochondrion;
Structure of mitochondrion;
What causes mitochondrial dysfunction?
Mutations in mtDNA
What diseases (although not necessarily the cause) is mitochondrial dysfunction associated with?
-Alzheimer’s Dementia
-Parkinson’s disease
-Huntington Disease
-Diabetes
-Cardiovascular disease
-Stroke.
-Autoimmune diseases (Sjogrens syndrome)
-Cancer
What structure is this?
What is the cytoplasm
The material between the cell membrane and the nuclear envelope
What does the cytoplasm do?
Not static – facilitates transport of material around cell: Cytoplasmic Streaming
In eukaryotes, what is contained in the cytoplasm and what is their function
Fibrous proteins in the cytoplasm known as the CYTOSKELETON
Maintains shape of cell
Anchors organelles
Moves cell
Controls internal movement of organelles
