Organelle and Cell Structure Flashcards
What are the three concepts of cell theory?
- The cell is the basic unit of structure and organization in organisms
- All living things are made up of one or more cells
- All cells come from pre-existing cells
What are viruses?
Viruses are obligate intracellular parasites.
Obligate - Restricted to a particular condition of life
Intracellular - within a cell
Parasites - Lives in host cells and obtains nourishments from it
What is the function of the capsid?
Protect the viral genome from damage
What is the function of the viral envelope?
Contains glycoproteins that help facilitate the attachment of the virus to receptors on the host cells cell surface membrane. Protects the virus from enzymes and chemicals.
Structure and function of nucleus.
Structure: Nucleus membrane is a double membrane and has nuclear pores. The outer membrane is continuous with the membrane of the rER.
Function: Controls all cell activity such as cell growth and repair of worn out organelles. Hereditary information is stored in the form of DNA. Stores DNA that is used as a template for DNA replication and transcription.
Nuclear envelope: Separate the contents from the cytoplasm.
Nuclear pores: Facilitates transport of materials in and out of the cell
Nucleolus: Contains rRNA genes thus it is the site of rRNA synthesis and assembly of ribosomal subunits.
Structure and function of ribosome.
Structure: Made of large and small ribosomal subunits. Each subunits is made of rRNA and ribosomal proteins. It is NON-MEMBRANOUS.
Function: Site of protein synthesis , using mRNA as a template.
Free ribosomes synthesize proteins to be used within the cytoplasm
Bound ribosomes attached to the rER synthesize protein to be secreted out the cell
Structure and functions of centrioles.
Structure: NON-MEMBRANOUS. Only found in animal cells. They are arranged perpendicular to one another. Each centriole is made of nine sets of three microtubules to form a cylinder. They are found near the nucleus.
Function: It replicates and move to opposite ends of the cell during cell division.
Structure and function of mitochondria.
Structure: DOUBLE-MEMBRANOUS. The mitochondria is enclosed in two membranes , the outer membrane is smooth but the inner membrane is convoluted , with cristae. The inner membrane is extensively folded into cristae . The outer and inner membrane are separated by intermembrane space. The mitochondrial matrix is enclosed by the inner membrane and contains 70S ribosome and enzymes.
Function: Site of ATP synthesis to release energy for cellular respiration.
Structure and function of chloroplast.
Structure: DOUBLE-MEMBRANOUS. It is enclosed by inner and outer membrane. Chloroplast contains thylakoids that stack on top each other to form a granum which are connected by intergranal lamealle.
Function: Site of photosynthesis.
What evidence supports the endosymbiotic theory?
BOTH HAVE
Naked and circular DNA
70S ribosome
synthesis their own protein
Are double membranous and have inner membranes with proteins similar to prokaryotes
Are about the same size as bacteria
Structure and function of rER.
Structure: Consists of interconnected flattened sacs that are made of phospholipids and are continuous with tubules. Appear rough under microscope due to ribosomes attached onto the membrane. Membrane of rER is continuous with the outer membrane of the nucleus envelope.
Function: Site of synthesis of proteins. Secretory proteins that will be secreted out the cell and membrane proteins that are incorporated into membrane.
Structure and function of sER.
Structure: Contains interconnecting membranous tubules. Appear smooth due to the absence of ribosomes. Both sacs and tubules are made of phospholipids and are interconnecting.
Function: Synthesis of lipids. Detoxification of drugs and poisons. Stores calcium ions.
Structure and function of Golgi Apparatus.
Structure: Contains stacks of flattened membranous sacs that are not inter-connected. The Golgi Apparatus has a cis face , which is nearer to the ER and a trans face.
Function: Sort , packages and further modification of proteins and lipids from rER and sER. Site of formation of lysosomes.
Structure and function of lysosome.
The lysosome is the organelle with the highest biochemical activity.
Structure: It consists of a small spherical structure containing hydrolytic enzymes.
Functions: Phagocytosis , Autophagy , Autolysis , Exocytosis.
Summary of secretory and lysosomal pathway by endomembrane system.
- A polypeptide is synthesized by a ribosome attached to the rER.
**2. The synthesized polypeptide enters the RER lumen via a protein receptor in the RER membrane. - Inside the RER lumen , the polypeptide folds into its globular structure.
- Secretory vesicles are chemically modified in the RER lumen.**
- It is then packaged in a transport vesicle and buds off the RER.
- Transport vesicles travels along the cytoskeleton with the use of ATP as energy. Transport vesicle fuses with cis face of Golgi Apparatus , where polypeptide is further modified.
- After further modifications , sorting and packaging in the Golgi Apparatus , vesicle buds out from the trans face of GA as either secretory , lysosome or membrane renewal vesicles.
