Chapter 8 - Cell Structure and Function Flashcards
Cell
basic building block of all living thigns
4 major components: DNA, cytoplasm, cell membrane, ribosome
-too small to see with naked eye
-need microscope to see
-virus is nonliving because it only has DNA/RNA and some proteins and needs host to reproduce
Light Microscope
most can magnify cells up to approx 400x (200 nanometer resolution)
Electron Microscope
provide 100,000x magnification with a resolution of 50 picometers
Conversions
10 mm = 1 cm
cm = 10 ^-2
mm = 10 ^-3
micrometer = 10 ^-6
nanometer = 10 ^-9
picometer = 10 ^-12
fentometer = 10 ^-15
Prokaryotic Cell
-simple, mostly single-celled (unicellular) organism that LACKS a nucleus or any other membrane-bound organelle
-has some organelles but not many
-DNA is in the cell’s central part: the nucleoid
-asexual reproduction
-bacteria, microalgae
-binary fission
Eukaryotic cell
multiple single-celled
-sexual reproduction
-yeast, plant, animal
-has a nucleus, organelles (endoplasmic reticulum, golgi complex, chloroplasts, mitochondria), chromosomes (several, rod-shaped)
-mitosis (cell division) and meiosis (sexual recombination)
Plasma Membrane
components: lipid bilayer, cholesterol, proteins
-“fluid mosaic” - not rigid, soft like underfilled water balloon, proteins move freely along surface
Microvilli
-appear on cells lining the small intestine
-increases the surface area available for absorption
-only on the area of the plasma membrane that faces the cavity from which substances will be absorbed
Nucleus
-houses the cell’s DNA and directs the synthesis of ribosomes and proteins
-stores chromatin (DNA and proteins) in the nucleoplasm (gel0like substance)
-nucleolus = condensed chromatic region where ribosome synthesis occurs
Chromatin and Chromosome
Chromosomes = structures within the nucleus that are made up of DNA, eukaryotic species have a specific number of chromosomes in the nucleus of each cell
-when cell is in the growth and maintenance phases of its life cycle, proteins are attached to chromosomes and assemble an unwound, jumbled bunch of thread
-unwound, protein-chromosome complexes are chromatin
Ribosomes
-cellular structures responsible for protein synthesis
-receive their orders for protein synthesis from the nucleus where DNA transcribes into messenger RNA (mRNA)
-mRNA travels to ribosomes, which translate code provided by sequence of nitrogenous bases in mRNA
Mitochondria
-cells powerhouses or energy factories, they are responsible for making adenosine triphosphate (ATP)
-muscle cells and the liver have a high concentration of mitochondria
-when cells don’t get enough oxygen, they don’t make much ATP, instead producing lactid acid accompanies a small amount of ATP made in absence of Oxygen.
Peroxisome
-small round organelles enclosed by a single membrane
-carry out oxidation reactions that break down FAs and AAs
-Detoxify poisons that may enter the body
-peroxisome in liver cells detoxify alcohol, glyoxisomes in plants convert stored fats into sugars
-plants contain different types of peroxisomes that play role in metabolisms, pathogens defense, stress response
Lysomes
-garbage disposal
-enzymes within lysosomes aid in breaking down proteins, polysaccharides, lipids, nucleic acids, and worn out organelles
-enzymes active at lower ph, many reactions that take place in cytoplasm could ot occur at lower ph
Cytoskeleton of Eurkaryotic Cells
-maintains the shape of the cell
-responsible for the movement of cells and organelles within cell
-made of 3 types of protein fibers (microtubules, microfilaments, immediate filaments)
Golgi Apparatus
-site of protein modification and shipping
-consists of several flattened, disc-shaped sacs called cisternae
-always closely associated with the endoplasmic reticulum (ER)
-transition vesicles from ER are picked up at the face of the Golgi Apparatus
-proteins modified within cisternae by the addition of polysaccharides and lipids
-condensing vesicles pinch off Golgi apparatus and are conveyed to lysosomes or transported out of cell
Membrane Transportation
- 1 of the most important functions of plasma membranes
Passive: molecules move from H to L concentration, requires large concentration gradient for significant levels of uptake, limited to only a few small molecules - Diffusion
-Osmosis
-Facilitated Diffusion (transport): carrier molecules (permease) to increase the rate of diffusion, net effect limited to movement from aera of H to L, generally more important in Euk than Pro
Active: same concept as passive but with Energy involved (ATP)
-ATP binding cassette transporters
-group translocation
-iron uptake
Hypertonic
cell decrease in size because water moves out (H to L)
Hypotonic
cell increase in size because water moves in (H to L)
Isotonic
no change in cell size because equal concentrations
Binary Fission
asexual reproduction by a separation of the body into two new bodies. In the process of binary fission, an organism duplicates its genetic material, or deoxyribonucleic acid (DNA), and then divides into two parts (cytokinesis), with each new organism receiving one copy of DNA
Mitosis
Replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained.
Meiosis
a type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes
