Chapter 3 (Good) - The Cell Flashcards
3 Major Parts of a Cell
- Plasma membrane - separates inside of cell from outside of cell 2. Cytoplasm - everything between the plasma membrane & the nucleus 3. Nucleus - control center; contains the cell’s DNA
3 Functions of Plasma Membrane
- Cell barrier - movement in & out of cell: movement determined by the cell 2. Selectively Permeable - some things are allowed through 3. Cellular Communication
Structure of Plasma Membrane
Fluid Mosaic Model–model to describe plasma membrane; fluid - refers to liquid & moves around; mosaic - refers to proteins which give structure & function to plasma membrane; so many shapes & functions; diversity
Fluid Mosaic Model Structure contains:
3 Lipids: 1. Phospholipids bilayer - make up bulk of membrane 2. Cholesterol 3. Glycolipids - part lipid part carb; carb attached to lipid 3 Proteins: 1. Periphereal proteins - loosely attached; on side 2. Integral proteins - imbedded or inside 3. Glycoproteins - carbs attached to proteins (stick outside of cell)
“Glyco” part of glycolipids & glycoproteins
Glycocalyx - carbs on outer surface of plasma membrane; Function: cellular recognition
Transport Processes - how things cross the plasma membrane (lipid barrier); selectively permeable
- Passive Processes - does not require chemical energy; moves from high to low concentration 2. Active Processes - needs ATP (requires chemical energy)
3 Types of Passive Processes - driving force is concentration gradient
- Simple Diffusion - very few things can cross bc lipids (nonpolar); must be nonpolar & small; ex. O2 & CO2 2. Facilitated Diffusion - polar molecules (ions-charged particles) cannot cross by simple diffusion but may cross by facilitated diff w/help of a protein; Needed for facilitated diff - protein channel - places where ions can cross & protein carriers - amino acids, glucose; needs a helping protein to cross; 3. Osmosis - diffustion of water across a selectively permeable membrane; 3 kinds of solutions: Isotonic, Hypotonic solution & Hypertonic solution
Diffusion
passive process; depends on concentration gradience; things move from high to low concentration
3 Different Kinds of Solutions for Osmosis:
- Isotonic - same solute concentration; mixture is matched to cell; H2O concentration is same inside cell & outside cell; no net movement of water: osmosis does not occur; cell maintains its shape 2. Hypotonic solution - lower solute concentration; solution w/very few solutes (like distilled water); very few salts; lower H2O in cell & highest water in solution; H2O moves into cell & cell swells up & could burst (lyse) 3. Hypertonic solution - higher solute concentration; put into very salty solution; less H2O surrounding cell & higher amount in cell; H2O goes out of cell & cell shrinks
Water follows
salts; wherever there is more salts , water will be sucked into it
Active Processes;
we want things to move from low concentration to high concentration; usually low to high concentration–which is not favorable
3 Types of Active Processes:
- Primary Active Transport 2. Secondary Active Transport 3. Vesicular Transport–a. exocytosis & b. endocytosis –1. phagocytosis, 2. pinocytosis, 3. receptor- mediated endocytosis
Primary Active Transport (Active Process) - uses ATP; from low - high
ex. Na+ K+ pump -moves 2 substances in diff directions from low to high; found in every single cell in body; protein Na+ - pumped OUT of cell (from low -high); K+ - pumped INTO cell (from low -high); very little Na+ in cells & very little K+ outside cells & losts of salt outside cells; ATP - ase - enzyme that hydrolizes ATP
Secondary Active Transport (Active Process)
only works when primary is working; uses concentration gradient that was already established; Na+ tends to want to go back in cell bc it goes from high - low; will go in through Secondary Active transport & will pump out Ca2+ or can move Na+ into cell & H+ out; can move glucose or amino acids in as Na+ moves in; indirectly uses ATP; links movement of one ion w/movement of 2nd particle by concentration gradient that has already been established; relies on concentration gradient; does not directly use ATP but does not work unless Primary Active Transport setup concentration gradient
Vesicular Transport (Active Process)
refers to vesicles; how we bring fairly bulky materials across membrane w/assistance of vesicles; uses vesicles (membrane sacs); uses ATP 1. exocytosis - uses vesicles to transport substances out of cell; the way proteins, hormones leave the cell 2. endocytosis - uses vesicles to transport substances into cell 3 different mechanisms of endocytosis- phagocytosis, pinocytosis, receptor-mediated endocytosis
3 Different Mechanisms of Endocytosis (part of Vesicular Transport)
- Phagocytosis - “cellular eating”; how our body is defended; engulfing of large particles or cells & break it down 2. Pinocytosis - “cellular drinking”; taking in fluid that surrounds cell 3. Receptor Mediated Endocytosis - specific; targets one type of molecule; has receptors; brings a specific molecule into cell using vesicles
Cytoplasm
consists of cytosol, organelles & sometimes inclusion
Cytosol
colloid (heterogeneous); salts, proteins, amino acids
Organelles
subcellular structures that have specific functions in the cell
Inclusions
stored nutrients (not dissolved; not part of cytosol); not in all cells; found in very few cells ex. lipid droplets–largest cell in body–lipids (fat cell) ex. glycogen granules - found in liver & muscle cells
Nucleus
control center, holds the cell’s DNA; largest of all organic compounds
Nuclear envelope
double membrane that surrounds the nucleus
Nuclear pores
openings in the nuclear envelope; protein channels; big pores
Nucleolus
assembles the ribosomes (made of protein & ribosomal RNA)
Chromatin
combination of DNA & histone proteins; chemicals of which chromosones are made of; histone proteins - packing proteings that help organize the DNA
Chromosomes
structures made of chromatin (x-shaped)
Genes
segments of DNA that hold info for one characteristic (trait); each chromosome has a bunch of genes associated w/it
Centrosomes
region centrioles are located in; Function: microtubule- organizing center
Flagella
longer than cillia; allows cell to swim (ex. sperm cell)
Cillia
moves substances outside cells; cillia pushes mucous out of respiratory tract
Cytoskeleton
made of fibrous proteins; maintains cell shape; a. microfilaments- protein actin; muscle contraction b. intermediate filaments - protein keratin; in hair, nails & epidermis (outer layer of skin) c. microtubules - protein tubulin; anchors organelles; move things in cells
Peroxisomes
membrane sac; contains oxidases + catalases; neutralizes free radicals free radicals - highly reactive molecules–unpaired electrons; disrupts structures in cells; happens bc of metabolism
The Cell Cycle
cycle of the cell as it grows & then divides; 1. Interphase 2. Mitotic Phase
Interphase (Sub phases of The Cell Cycle)
- G1 - growth 2. S - growth; DNA synthesis phase: DNA replicated 3. G2 - growth; makes final preparations for cell division
Mitotic Phase (The Cell Cycle) - divides into 2 identical cells
- Mitosis - division of the nucleus 4 subphases: (PMAT): a. Prophase b. Metaphase c. Anaphase d. Telophase 2. Cytokinesis - division of the cytoplasm
How Nucleus Controls Cells (Transfer of Genetic Info)
- Replication - makes DNA (DNA synthesis); identical copy of DNA is made; takes place during S phase of Interphase; only happens one time in cell cycle: takes place in nucleus; copies ALL genetic info 2. Transcription - makes messenger RNA (RNA synthesis); transfer of genetic info from DNA to mRNA; takes place in nucleus 3. Translation - makes protein (Protein synthesis); info from mRNA is used to make a protein; takes place in cytoplasm (ribosome); takes place outside of nucleus
mRNA
messenger RNA; DNA transfers some info to RNA; info is used to tell ribosome what kind of protein is to be built; DNA never leaves nucleus; replication takes place in nucleus
Order of Bases on DNA
holds the info that is copied; secret of how replication & transcription; errors in order of bases causes a mutation
Complementary Base-pairing (Replication)
- A (Adenine)…T (Thymine)
- C (Cytosine)…G (Guanine)
Covalent bonds hold these together
1st Step of Replication
DNA strands separate; easier to break hydrogen bonds (which is how the DNA strands are held together)
DNA Polymerase
main enzyme responsible for replication; puts down a brand new strand that is paired up; makes one new strand & pairs w/original strand; results in 2 identical DNA strands; new template & 2nd strand are identical
Example Template of Replication: Sequence of Original Strand/2nd Strand G...C T...A C...G A...T G...C
NEW SEQUENCE 1st strand/2nd strand C...G A...T G...C T...A C...G
Complementary Base-pairing (Transcription)
DNA/RNA--order of bases of DNA specifies what order of mRNA is. A (Adenine)...U (Urasil) T (Thymine)...A (Adenine) C (Cytosine)...G (Guanine) G (Guanine)...C (Cytosine)
Transcription -
takes place during Interphase (any phase); only transfers a little of info that cell needs; only transfers one gene’s info to make a mRNA (that carries info); 2 strands separate but only 1 strand acts as a guide
Example Template of Transcription: Sequence of Original Strand (DNA temp) G T C A G
NEW SEQUENCE New mRNA: C A G U C
RNA Polymerase
enzyme that makes RNA
Translation
mRNA leaves nucleus out thru nuclear pores & goes to ribosomes; mRNA provides instructions to ribosomes to build protein it needs going from bases to amino acids
Ribosomes (Translation)
reads 3 bases at a time on RNA & puts down 1 (of the 20) amino acids & then peptide bond links together 2 amino acids; order of bases on mRNA specifies order of proteins (amino acids); order of amino acids–primary structure–different amino acid lined up in specific structure
Because of Transcription & Translation…
every cell has same genetic make-up but each cell does something different
