Lecture Four - introduction into human cells Flashcards
Prokaryotic cells
single celled, no nucleus, example= eubacteria
eukaryotes
Animal and plant cells are examples
Single or multicellular, membrane bound, have a nucleus.
Structures found in most human cells
- Plasma membrane,
- RER
- Ribosomes
- SER
- Mitochondria
- Nucleus
- Secretory vesicles
- Lysosomes
- Centrioles
- Golgi apparatus
- Endosome
Difference between a cytoplasm and cytosol.
- Cytoplasm is everything within the cell except for the nucleus.
- Cytosol excludes ALL organelles within a cell.
Four classes of biological molecules found in cells
- Nucleic acids= DNA. RNA and nucleotides
- Lipids= fatty acids, triglycerides, Steroids
- Proteins= amino acids and polypeptides
- Carbs= monosaccharide, disaccharide. Polysaccharide
Nucleus structure
- Nuclear envelope= double membrane. Contains pores
- Nucleolus= site of ribosome synthesis.
- Chromatin (made up of DNA and protein). During cell division this condenses to form chromosomes
- largest organelle
Nucleus function
- Function= contains genetic information. Stores and transmits genetic information to the next generation of cells.
- Genetic information is coded in molecules of DNA.
- DNA is used to synthesize proteins.
Nuclear envelope structure
Double membrane containing pores
Nuclear envelope/ pores function
- Nuclear pores allow mRNA to leave the nucleus and enter the cytosol for translation.
- Proteins that modulate the expression of various genes in DNA move into the nucleus through pores.
Structure of RER
ribosomes bound to its cytosolic surface. Has a flattened sac appearance.
Role of the RER
Involved in processing and packaging proteins to send to the Golgi body.
Structure of SER
Smooth has no ribosomes on its surface. It has a branched tubular structure.
Role of the SER
Site of lipid molecule and steroid synthesis. It also plays a role in detoxification of certain hydrophobic molecules and stores and releases calcium ions involved in controlling various cell activities.
Role of ribosomes
Site of protein synthesis- involved in translation of mRNA into the primary structure of proteins- polypeptide chains.
Proteins are synthesized on free ribosomes and are released into the cytosol OR on ribosomes attached to the RER which then pass into the lumen of the RER.
Structure/positioning of ribosomes
- no membrane
- Made up of RNA and protein
- free floating or attached to surface of RER.
Golgi Apparatus structure
A series of membrane bound flattened sacs.
Golgi apparatus role.
Proteins arriving at the Golgi from the RER are modified and they pass from one Golgi compartment to the next.
The Golgi apparatus sorts the modified proteins into transport vesicles that travel to various cell locations.
Structure of mitochondria
- double membrane. the inner membrane fold to form the cristae.
- the matrix contains enzymes for aerobic respiration and also DN and ribosomes.
Role of mitochondria
- Participate in the process of aerobic respiration. Most energy that cells use are in the form of ATP made in the mitochondria by aerobic respiration.
Lysosomes structure and function
- Spherical
- Single membrane
- Fluid within the lysosome is acidic and contains a variety of digestive enzymes
- The digestive enzymes released from lysosomes are used to digest food, digest organelles and digest cells
Peroxisomes structure and function
- Dense oval bodies
- Single membranes
- Fatty acid oxidation and H2O2 detoxification
- Consume molecular oxygen and performs reactions that remove hydrogen from organic molecules including lipids, alcohol and potentially toxic ingested substances
Role of endosomes
- Vesicles pinch off the plasma membrane and travel to and fuse with endosomes.
- The endosomes will pinch off vesicles that then move to other cell organelles or return to the plasma membrane.
- Endosomes are involved in sorting, modifying and directing vesicular traffic.
Flagella
- protrude from cell body
- rotate/whip like motion to allow the cell to move
What is the cytoskeleton?
the network of protein filaments found in the cytoplasm
the role of the cytoskeleton
associated with processes which maintain and change cell shape and produce cell movements.
name the three classes of cytoskeletal filaments in order of size of diameter (smallest first)
actin filaments/ microfilaments, intermediate filaments and microtubules.
Actin filaments and microtubules share a property. What? What is the importance of this?
- Actin filaments and microtubules can be assembled and disassembled quickly. This allow a cell to alter these components of its cytoskeletal framework quickly according to changing requirements.
intermediate filaments are less…
…readily disassembled
Describe actin filaments
- Actin filaments are made of monomers of the G-actin protein. Functions= determine cell shape, cell division and muscle cell contraction.
Describe intermediate filaments
- Intermediate filament is made from twisted strands of several proteins. Role= cell shape and help to anchor the nucleus. They provide strength to cells.
Describe microtubules
- Microtubule is hollow tube made from tubulin. They are the most rigid of the cytoskeletal filaments. Centrioles are made up of microtubules, they are important for the production of spindle fibres in cell division.
What are cilia and how are their structures similar to centrioles?
- Slender protuberances/ hairlike extensions found on the surface of cells. They have a central core of microtubules similar to in centrioles.
