Cell Biology Flashcards
Cytology vs cell physiology
Study of cellular structure vs study of cellular function
Resolution
The ability to distinguish between two points
Most common way to look at cells
Light microscope.
- Compound
- Dissecting
Can view the cell mitochondria and 1 micro meter
Scanning tunneling microscope
Very new technology can view 0.001 micrometers. The size of a protein molecule.
Confocal microscope
Higher resolution. Optically slices tissues so there is no out of focus tissue.
Electron microscope types
Transmission, scanning, x ray detector
Nuclear division
Mitosis
Cytoplasmic division
Cytokinesis
Mitosis
One parent somatic cell gives rise to two identical daughter cells
Meiosis
Reproductive cell division that produces eggs and sperm. Occurs only in the testes and ovary.
Largest organelle in a cell
Nucleus (surrounded by 2 membranes)
DNA polymerase creates DNA in which direction
DNA polymerase can only add onto the 3’ OH end of a DNA strand.
Post-transcriptional modification to mRNA
- 5’ cap
- 3’ poly A tail
- Splice out introns, leaving only exons to exit the nucleus.
Polyribosome
10-20 ribosomes together
Where can ribosomes be found
Free in the cytoplasm, on the RER, and inside the mitochondria to synthesize mitochondrial DNA
Polar amino acids
Have OH groups and hydrogen bonds
Primary protein structure
Single strand of amino acids
Secondary protein structure
Alpha helix or beta pleated sheets
Tertiary structure
Three dimensional structure
Quaternary
Multiple proteins consisting of a variety of bonds and interactions
Ionic bond
Bond between a positive and negative molecule
Covalent/disulfide bond
S-S
What does the smooth ER synthesize
The smooth ER is a highly branched network that synthesizes Phospholipids, steroids, fats and detoxifies harmful substances (alcohol or drugs)
Function of lysosomes
Autolysis (lysosomal damage after death)
Autophagy (recycles own organelles)
How are peroxisomes formed
Formed from pre-existing peroxisomes Smaller than lysosomes Breaks down amino acids and fatty acids. Oxidizes toxic substances such as alcohol and formaldehyde. Contains catalase which decomposes H2O2
Mitochondrial is the only organelle that can
Self replicate
Mitochondrial concentrations increases when
Need for ATP increases. Metabolically active cell
How many genes does mitochondria have and in what shape
37, circular
Why is mitochondria only inherited from mother
When the sperm fertilizes the egg, the sperm tail breaks off upon entering the oocyte. All of the sperms mitochondria are located in the tail.
How much percent of the cell is cytosol
55%
mostly water with other components such as
-large organic molecules (proteins, carbohydrates, lipids)
-Small organic molecules (simple sugars and ions)
Site of many important chemical reactions
Protein subunit of :
Actin microfilament
Intermediate filament
Microtubule
Actin- G actin (thinnest)
Intermediate filament- Several proteins
Microtubule- Tubulin (thickest cytoskeleton filament)
Cytoskeleton functions
- Cell support and shape
- Organization of chemical reactions
- Cell and organelle movement
- Continually reorganized
Role of microfilaments
- thinnest
- made of G actin
- Used for locomotion and division
- Supports microvilli
Role of intermediate filament
Is composed of several different proteins
Role is to anchor organelles
Role of Microtubules
- large cylindrical structure composed of tubulin
- Creates flagella, cilia, and centrosomes
Centrosomes
Composed of 2 centrioles that are 90 degrees to each other. They are found near the nucleus in the pericentriolar area. This is the formation site for the mitotic spindle and microtubules organizing center.
Structure of cilia and flagella
Pair of microtubules
Covered by cell membrane
Cilia- use for respiratory system. Short and multiple microtubules.
Flagella- use for reproductive system. Long and single.
Cyclin
A protein that builds up during interphase and triggers mitosis
Necrosis
Cell death caused by injury or infection
Ubiquitin
A small peptide that can attach to proteins that need to be targeted for degradation. This peptide then can direct the marked protein to a complex known as a proteasome (contains proteases), which unfolds the protein and breaks it down.
Hyperplasia
Increased number of cell divisions. Occurs due to carcinogens, x rays of viruses and may cause cancer.
The plasma membrane is composed of 50% __ and 50% __
Lipids and proteins.
Lipids are barriers to entry of exit of polar substances.
Proteins are gate keepers and regulate traffic.
Glycolipids in the cell membrane
- Amphipathic molecules that are integral/intrinsic cell membrane proteins.
- Extend into cell membrane.
- Comprises 5% of the lipids in the cell membrane
- Carbohydrate groups form a polar head only on one side of the membrane facing the aqueous fluid.
The lipid bilayer is permeable to what
Nonpolar, small, uncharged molecules. Oxygen, Co2, steroids.
Function of transmembrane proteins
Act as specific channels and allow small and medium polar and charged particles through.
Does cholesterol stiffen or loosen the lipid bilayer
Stiffens by forming hydrogen bonds with neighboring phospholipid heads.
-Comprises 20% of the cell membrane lipids
Shape of cholesterol
Stiff steroid ring and hydrocarbon tail are non polar and hide in the middle of the cell membrane.
