Cell notes Flashcards
Plasma membrane-
cell membrane
cell membrane Structure:
thin outer membrane. Called a lipid bilayer- double layer of lipids
Purpose:
cell membrane
Separates metabolic activities inside the cell from random events outside cell. Still allows materials in and out
Nucleus
membrane bound sac in eukaryotic cells that contains DNA
Nucleoid
region in prokaryotic cells that contains
DNA that is not enclosed in a membrane
Cytoplasm
Everything in between the plasma membrane and the region of DNA. Contains a semi-fluid matrix (called the cytosol) and
structural components with specific jobs (organelles)
Why can’t cells grow infinitely large?
surface to vol ratio
surface-to-volume ratio
if a cell expands in diameter during growth,
then its volume will increase faster than its surface area
why can’t a cell live if the cell gets too big and vol increases faster than surface area?
The inward flow of nutrients and outward flow of wastes
will not be fast enough to keep up with the metabolic activity of the cell, and it’ll be hard to move materials thru cytoplasm
compound light microscope structure
two or more sets of glass lenses bend waves of light
passing thru a specimen
compound light microscope ability
Views objects that are thin enough for light to
pass through them
electron microscope structure
Structure: use magnetic lenses to
bend and defract beams of electrons
Transmission electron microscope:
electrons pass through a
specimen and are used to make images of its internal details
Scanning electron microscope:
a beam of electrons pass back
and forth across a surface of a specimen with a thin metal coating
Two domains of prokaryotic cells:
Bacteria and Archaea
Size of prokaryotic cell
not much wider than a micrometer, no more than a few micrometers long
Cell wall permeability prokaryotic
permeable to dissolved substances
Flagella:
movable structure that helps move prokaryotic cells through
fluid habitats
characteristics cytoplasm–prokaryotic
contains many ribosomes, DNA is concentrated in a
nucleoid region, some have plasmids
plasmids
small circles of DNA (separate from main DNA)
advantages of partitioning the cell interior into many organelles:
Outer membrane encloses a microenvironment for cell
activities, allowing each organelle to do its own job. Specialized organelles interact, keeping a whole cell functioning as it should.
DNA in the nucleus
contains the instructions for encoding proteins
functions of nucleus DNA
- Prevents the DNA from getting
tangled with the cytoplasm, Can control what moves in and out of the nucleus from the cytoplasm
Nuclear envelope-
Consists of double membrane system in which two lipid
bilayers are pressed against each other
Nucleolus
produces ribosomes
ribosomes
get info from RNA about DNA and make proteins
Chromosomes stages
Chromatin + chromosomes
Chromatin
all of a cell’s DNA and its associated proteins
chromosomes
a specific section of a double-stranded DNA
molecule and its associated proteins
- Endomembrane System
ER, Golgi bodies, vesicles
- Endoplasmic reticulum:
Flattened channel that starts at nuclear envelope and folds back on its own repeatedly
Rough ER
Has many ribosomes attached to its
outer surface. Allows polypeptide chains that are produced by
ribosomes to enter where they can be modified by enzymes