bioflashcards4
Cell
the smallest unit that shows properties of life which means it has the capacity for metabolism, homeostasis, growth, and reproduction. All start out with a plasma membrane, a DNA-containing region, and cytoplasm.
Eukaryotic Cell
Is divided into various functional compartments, including the nucleus.
Prokaryotic Cells
Are smaller and simpler cells; they do not have a nucleus.
Plasma Memebrane
A cells outer membrane. It separates metabolic activities from events outside the cell, but does not isolate the cells interior. Water, carbon dioxide, and oxygen can still pass freely across it. Some substances can cross through with assistance from membrane proteins however others are kept out entirely.
Nucleus
A double-membraned sac which hold an eukaryotic cell’s DNA.
Nucleoid
The region where the DNA inside a prokaryotic cell is concentrated inside the cytoplasm.
Cytoplasm
Is the semifluid mixture of water, ions, sugars, and proteins between the plasma membrane and the region of DNA.Cell compartments and other components are suspended in cytoplasm.
Ribosomes
Structures on which proteins are built.
Lipid bilayer
the structural foundation of the cell membranes. It is double layer of lipids organized so that their hydrophobic tails are sandwiched between their hydrophilic heads. Proteins in the bilayer carry out the membranes functions.
Phospholipids
The most abundant type of lipid in the cell membrane. Each has a phosphate-containing head an two fatty acid tails. The polar head is hydropholic (attracts water molecules) and the non polar tails are hydrophobic (repel water molecule). This causes the hydrophobic tails to be sandwiched between their hydrophilic heads making up the cell membrane.
Examples of cells that can be seen from naked eye?
Egg yolk, watermelon tissues, and amphibian and fish eggs.
Surface-to-volume ratio
An objects volume increases with the cube of its diameter, but it’s surface area increases only with the square. So it’s volume increases faster then surface area and the plasma membrane must handle exchanges with much more cytoplasm slowing down the inward and outward flow of nutrients. If this slows down too much the cell may die. Many cells find ways to increase their surface area (long and thin or frilly with folds) to keep up with an actives cells metabolism.
The Cell Theory
- All organisms consist of one or more cells 2. The cell is the smallest nit that retains the properties of life 3. Each new cell arises from another cell.
Light Microscopes
They rely on visible light to illuminate objects. Light is focused and magnified with curved glass lenses. Light passes through the specimen so only cells that are thin enough for light to pass through them will be enhanced.
Micrographs
Photos of images enlarged by microscopes.
Fluorescence Microscope
The cell or molecule is the light source and it emits energy (fluoresces) in the form of light when a laser beam is focused on it. Chlorophyll’s fluoresce naturally.
Wavelength
The distance from the peak of one wave to the peak of the one behind it. This limits the power of any light microscope because structures which are smaller then one half of the wave length are too small to scatter light waves.
Electron Microscopes
Reveals smaller details because instead of using light to illuminate samples they use electrons which travel in smaller wave lengths.
Transmission Electron Microscopes
Electrons form an image after they pass through a thin specimen. The internal details appear as shadows.
Scanning Electron Microscope
Direct beam of electrons back and froth across a specimen which has been coated with a thin layer of gold or another metal. The metal emits both electrons and x-rays which re converted into an image of the surface.
Fluid Mosaic Model
describes the organization of cell membranes.
Passive Transporters
Allows ions r small molecules to cross a membrane to the side where they are less concentrated. Open or grated channels. Ex. Porins; glucose transporter.
Active Transporters
Pump ions or molecules through membranes to the side where they are ore concentrated. Requires energy input as ATP. Ex. Calcium pump; serotonim transporter
Receptors
Initiate change in cell activity by responding to an outside signal. Ex. Insulin receptor; B cell receptor
Cell Adhesion Molecules
Help cells stick to one another and to protein matrixes tat are part of tissues. Ex. Integrins; cadherins
Recognition proteins
Identity cells as self (belonging to one’s own body or tissue) or non-self (foreign to the body)
Communication Proteins
Join together and form cytoplasm-to-cytoplasm junctions through which ions and small molecules pass freely and quickly between adjacent cells. Ex. Connexins in gap junctions.
Membrane compostition
Membrane composition differs dependent on the cell’s functions. The two surfaces of the lipid bilayer are even different.
Two domains of prokaryotic cells
Bacteria and Archea
Cell Wall
Found in prokaryotic and plant cells. Surrounds the plasma membrane and is a rigid yet porous structure.
Flagella
slender cellular structures used for motion. Bacteria use them as a propeller whereas in a eukaroytic cell they bend like a whip and have a distinctive internal structure.
Pili
Protein filaments project from the surface of some bacterial species. They help cells cling to or move across surfaces. ‘sex’ pili attach will attach to another bacterium, shorten, reel in the cell, and transfer the genetic material.
Biofilms
Single celled organisms live in a shared mass of slime such as a layer of secreted polysaccharide and glycoproteins. In a biofilm multiple species will live in their own feces.
Nucleus
Protect and control access to the DNA.Has a membrane.
Endoplasmic Reticulum
Extension of the nuclear envelope. Routing, modifying new polypeptide chains; synthesizing lipids; other tasks. Has a membrane.
Golgi Body
Modifying new polypeptide chains,;sorting, shipping proteins and lipids. Has a membrane.
Vesicles
Transporting, storing or digesting substances in a cell; other functions. Has a membrane.
Mitchondrion
Makes ATP by glucose breakdown. specializes in aerobic respiration. Has a membrane.
Chloroplast
Making sugars in plants, some protists. Has a membrane.
Eurkaryotic Ribosomes
Assembling polypeptide chains. No Membrane.
Cytoskeleton
Contributes to cell shape, internal organization, and movement. Made up of microtubles, microfilaments, and intermediate filaments.
Nuclear-envelope
Pore-riddled double membrane that controls which substances enter and leave the nucleus
Nucleoplasm
Semifluid interior portion of the nucleus
Nucleolus
Rounded mass of proteins and copies of genes for ribosomal RNA used to construct ribosomal subunits
Chromatin
Total collection of DNA molecules and associated proteins in the nucleus: all the chromosomes
Chromosome
One DNA molecule, duplicated or not, and the many proteins associated with it
Rough ER
Ribosomes attached to it, some of the polypeptide chains assembled on ribosomes enter the ER. Others become a part of the ER membrane itself.
Smooth ER
No ribosomes. Makes most of the lipids that get incorporated into the cell membrane.
Golgi Body
receives, processes, and repackages substances that arrive in vesicles from the ER.
Vesicles
Transport substances to parts of the cell. Exocytic vesicles move waste out and endocytic vesicles bring nutrients, water, and other substances in.
Lysosomes
Dijest and recycles materials.
Central Vacoule
Amino acids, sugars, toxins, and ions accumulate and keep plant cells firm.
Peroxisomes
Contain enzymes which digest fatty acids and amino acids. They break down hydrogen peroxide to water and oxygen or they will use their enzymes to breakdown alcohol and other toxins.
Centrioles
Produces and organizes microtubules.
Plasmodesma
communication between adjoining cells
Secondary wall
formed as the primary cell wall develops and begins to secrete material to a new secondary cell wall. One material deposited in lignin which makes cells stronger and more waterproof.
extracelluar matrix
provides structural support to animal cells
cell junctions
allow cells to connect with each other to share material and send and receive signals with each other. (plasmodesmata in plants)
three types of cell-to-cell junctions
tight (link most body tissues and seal cells together), Adhering (cells anchor to one another), gap (connect cytoplasm of adjacent cells. substance flow quickly through these open channels)
Microtubules
long hollow cylinders consisting of many subunits of the protein tubulin. They assemble and disassemble as needed.
Microfilaments
Consist of globular protein actin. Change shape of eukaryotic cells.
Intermediate Filaments
Most stable part of the cytoskeleton. Strengthen and maintain cell and tissue structure.
Cilia
whiplike structures which propell cells through fluid.
False Feet
pseudopods move cell and engulf prey.
