Module 1 Lecture 1 - Cell Structure and Function Flashcards
What does Theodor Schwann state about the cell?
- The cell is the smallest structure and functional unit that can carry out life processes
- The activities of each cell depend on specific structural properties (movement, changing shape, abundant in organelles, etc)
- For an organism to function it depends on the collective structure and functions of all the cells within it.
- Cells of all organisms are practically similar in structure and function due to them having to keep the organism alive
- Cell is the basic unit of life
What does it mean when an organism depends on the collective structure and function of all the cells
It means that each cell is unique and provides something important to the organism
i.e. Immune cells provide immunity, skin cells provide us with skin, adipose cells provide us with fat to keep warm, etc.
What are the only exceptions to not having a cell?
Viruses and prions
How many different types of cells are there? List some examples
200 types of cells - immune cells, reproductive cells, smooth muscle cells
How many total cells are in the human body (not classified into)?
Trillions of cells (not classified into separate types of cells)
Three common/shared features of every cell?
Contain: nucleus, cytosol, and plasma membrane
How does the plasma membrane look?
Thin and membranous
Purpose of the plasma membrane?
To act as a barrier/boundary by keeping each cell enclosed/protected while providing a fixed environment inside the cell
What is the plasma membrane composed mostly of?
Lipid (fat) bilayer
What is the plasma membrane studded with?
It has proteins studded around the membrane
What is the purpose of the proteins on the plasma membrane
Helps facilitate movement of molecules in and out of the cell
Why is the plasma membrane known to be selectively permeable?
Although it acts as a barrier, it allows for certain nutrients and molecules to move through; hence being selective
What is the Nucleus?
The nucleus is the “brain” of the cell because it holds the genetic material of the cell that allows for duplication
Where is all the genetic information encoded in order to make proteins?
Nucleus
DNA stands for?
Deoxyribonucleic acid (no oxygen attached to the carbon atom)
What is the Endoplasmic Reticulum?
Large organelle; a connected mesh/network of a fluid filled membranous system
Purpose of the Endoplasmic Reticulum?
To produce proteins and lipids
How does transcription work?
1) DNA begins to unwind due to RNA polymerase and pre-mRNA transcript is made.
2) pre-mRNA is processed into mRNA and it sent out of the nucleus into the cytosol
How does translation work?
1) After leaving the nucleus it attaches to a ribosome which has rRNA and proteins
2) Ribosome moves down the mRNA while reading it and tRNA molecule one by one brings amino acids creating a polypeptide chain
Features of Rough ER
Studded with ribosomes (helps mRNA turn into a protein)
What does the Rough ER do?
Creates proteins to be released outside the ER or keep it inside the plasma membrane or for other cell components
Feature of Smooth ER
Does not have ribosomes but it has reticular like tubules for an increased surface area
Role of the Smooth ER
Package the secretory product (proteins from the rough er) into transport vesicles; bud off to the Golgi complex
What does the golgi complex look like?
Stack of flattened, slightly curved, bounded by the membrane
How is the Golgi complex connected to the ER
Vesicles from the Smooth ER carrying secretory product fuses with the Golgi complex
Role of the Golgi Complex
The golgi complex modifies, packages and overall distributes those proteins into different vesicles out the golgi
Where are these new vesicles carrying the proteins going?
Either to plasma membrane, lysosome (recyclable) or outside of the cell
What do Lysosomes look like?
They are small and bounded by the membrane
What are Lysosomes known for?
Containing thousands of enzymes
What type of organelle is a lysosome?
Degradative + membrane-enclosed organelle
What are the enzymes in lysosomes called?
Hydrolytic enzymes (common name for the multiple types of hydrolytic enzymes that exist)
What system does the lysosome act as?
It’s like the digestive system because it breaks down complex macromolecules into smaller molecules
What other function do lysosomes have other than digesting organic molecules?
Destroying foreign substances and cellular debris
What are peroxisomes?
Membrane-enclosed sacs that have oxidative enzymes
What are oxidative enzymes?
They oxidize a substrate - detoxify it
What is an organ that has tons of peroxisomes and why?
The liver has tons of peroxisomes; alcohol is a foreign toxic substance which peroxisomes react to and oxidize to decrease the harmfulness of it
Why do some cells have more organelles than others?
Some cells will have more organelles than others because they have more of a use for them
What do Centrioles look like?
Cylindrical structures at right angles to each other
What are centrioles found in?
In centromeres - these are what are used for cell division
What are centrioles made of?
Protein called Microtubules
Role of centrioles?
During cell division the centrioles form microtubules which are also known as mitotic spindles
What are mitotic spindles? What are they used for?
Mitotic spindles are built of microtubules and act as a “rope” to segregate chromosomes into daughter cells in mitosis
How are flagella and cilia connected to centrioles?
Flagella and cilia are made from centrioles which allows it to move around.
What do mitochondria look like?
Rod-shaped or oval shaped structure (size of bacteria)
How many membranes is the mitochondria enclosed by?
2 membranes
What are the names of the membranes enclosing the mitochondria?
Inner and outer mitochondrial membrane
What is the cristae?
It is the inner mitochondrial membrane folding to increase the surface area
What are the studs on the inner mitochondrial membrane
Proteins apart of the electron transport chain
What is the Matrix?
Centre of the Mitochondria; inner cavity filled with a gel-like solution
What is the Matrix projected (protruded) from?
Cristae
