Chapter 3 Flashcards
Two types of cells
- Somatic
2. sex (sperm and oocytes)
plasma membrane
•where is it located
•definiton
- outside the cell
* lipid bi layer that separates inside of the cell from surrounding extracellular fluid
2 subdivisions of the cytoplasm
- cytosol (liquid component)
2. Organelles (intracellular structures)
Nuclear envelope
•definition
•location
- membrane that surrounds the nucleus and separates it from the cytosol
- outside the nucleus
Nucleolus
•location
•what is it
•function
- inside the nucleus
- translucent nuclear organelle
- synthesizes ribosomal RNA
Nucleoplasm
•location
•what is it
- inside the cell
* fluid containing nuclear matrix
Nuclear matrix
Provides support
How is DNA organized in the nucleus
DNA is coiled around histone proteins to form a nucleosome
Chromosomes
•formula
•structure of non dividing
•structure of dividing
- DNA + proteins = chromosomes
- loose coils (chromatin)
- tight coils (ind. chromosomes can be seen under the microscope)
Mitotic phase (M) •2 types
- Mitosis
2. cytokinesis
Mitosis
•definition
•where does it occur
•what about the DNA
- division of nucleus
- occurs in somatic cells
- duplicated DNA is distributed equally between 2 daughter cels
Cytokinesis
Division of cytoplasm to form 2 separate cells
Interphase
•definition
•3 phases
•what does it determine
• where cell spends most of its time carrying out normal functions;when ready to divide it enters G1
1. Gap1
2. Synthesis
3. Gap2
•the time spent in interphase determines the rate of cellular division
Gap 1
cells replicate organelles and increase volume of cytosol
Synthesis
DNA duplication is performed
Gap 2
Centrioles replicate (cell division machinery)
G0
only occurs in cells that do not replicate (neurons)
•specialized cell functions
How does a dividing cell ensure that each daughter cell recieves an exact copy of the parent cell DNA?
Through DNA replication
3 steps of DNA replication
- DNA strands unwind
- DNA polymerase attaches to complimentary DNA nucleotides along each strand (multiple polymerase enzymes will bind DNA)
- Produces 2 identical copies of original DNA
What enzyme is responsible for unwinds the DNA?
Helicase
DNA polymerase •what is it •moves in what direction •what happens to 1 strand •what happens to the other strand
- responsible for DNA replication
- 1 direction
- One strand is produced in a continuous fashion
- the other strand is produced in segments and joined together by a “ligase”
Interphase
- End of G2 phase of cell cycle
* DNA exists as duplicated chromatin
Metaphase
•Chromosomes align on equator of the cell
Centromere
Where sister chromatids are connected to eachother
Anaphase
- Chromosome and centromere splits
- Chromosome are pulled to opposite poles
- Chromosome movement stops after arriving near the centrioles
Telophase
- Marks end of mitosis
- Nuclear division is over
- Nuclear membrane re-forms
- Chromosomes uncoil
3 components of the plasma membrane
- Lipids
- Proteins
- Carbohydrates
Lipids in the plasma membrane •how much % does it make up •what type of lipids are present •arrangement •function
- 42%
- Phospholipids and cholesterol
- Bi-layer
- barrier - maintain differences between outside and inside
What is the function of cholesterol in the bi-layer?
it is rigid to it provides structure to the membrane
Proteins in the plasma membrane
•how much % does it make up
•2 types
•55%
- Integral
- Peripheral
Integral proteins
Part of membrane structure that is embedded and cannot be removed easity
Peripheral proteins
Bound to inner or outer surface of membrane
Carbohydrates in the plasma membrane •how much % does it makeup •where is it located •what is it known •what is it used for
- 5%
- associated with outer surface only
- Known as glycocalyx
- used for communication
Function of the plasma membrane
- Barrier
* Selectively permeable-permits the passage of some materials while restricting the passage of others
4 types of membrane transport
- Diffusion
- Filtration
- Carrier mediated
- Vescular transport
Diffusion •active or passive •definition •what is the driving force •three types
•passive •movement of a substance from an area of high concentration to an area of low concentration •molecules are in motion 1. Simple 2. Channel mediated 3. osmosis