Module 1.3: The Cell Flashcards
The cell
1) basic & smallest unit of life
2) can carry out all activities associated with life
Metabolism
The chemical reactions that take place inside of the cell
What is cell theory?
(1) cells are the basic living units of organization in all organisms
(2) all cells come from other cells
Organelles are
- small specialized structures within the cell
-cell as factory (organelles would be each individual department contributing to the cells life functions)
Prokaryotic cells
-(also called prokaryotes)
-considered simple cells
-have three defining characteristics: (1) size, (2) non-enclosed genetic material and (3) lack of organelles and other internal membrane bound structures.
Prokaryotic cells are typically smaller than eukaryotic cells
- Most are between 1-10 (micrometers)
- 1/30,000 of an inch
-cannot be seen with the naked eye.
The DNA of a prokaryotic cell is not
enclosed within a nuclear membrane (prokaryotic means “before the nucleus”).
genomic material remains unbound within the cytoplasm
The area where this genetic material is located is referred to as the** nucleoid**
cytoplasm
(interior) of the cell
Ribosomes are responsible for
linking together amino acids, as specified by RNA, in order to generate proteins
Prokaryotic cells do not contain
organelles
Beyond the plasma membrane, the cell wall
is rigid in varying degree depending on the species.
Fimbriae
are protein structures located on the outside of the cell that are used for attachment to other cells.
Flagella
are whip like structures found on some prokaryotes and serve as a mechanism of movement.
Glycocalyx
is a glycoprotein or glycolipid outer coating that allows for protection.
The “coat” that protects the cell
Eukaryotic cells are more
complex than prokaryotic cells
The Nucleus
surrounded by a porous, double membrane (envelope) (two layers of walls)
is the most prominent organelle in the cell
Enclosed in the nucleoplasm
Ribosomes are complexes
of tiny manufacturing plants that assemble proteins.
Genes
The information necessary to determine which proteins a cell manufactures
found in specific sequences of nucleotides called “genes”
Endoplasmic reticulum (ER)
extension of the outer membrane of the nucleus
Rough endoplasmic reticulum (RER)
Part of ER that has ribosomes attached. Ribosomes appear bumpy
Smooth endoplasmic reticulum (SER)
Part of the ER which is responsible for the synthesis of lipids, steroids, and phospholipids
What do transport vesicles do?
Carry protein & lipids from the ER to Golgi apparatus
Lysosomes (“lysis” means to disintegrate)
are membrane-enclosed organelles that contain hydrolytic enzymes capable of degrading unwanted cellular debris such as proteins, lipids, nucleic acids and carbohydrates.
autophagy
Once cellular organic matter is broken into their building block monomers, these molecules can later be recycled into new biomacromolecules in a process called
Mitochondria
are double membrane-enclosed (phospholipid bilayer) organelles that are the site of cellular respiration.
Cellular respiration is
the process of using oxygen to generate ATP. Thus, the mitochondria can be considered the ‘power house’ of the cell.
Peroxisomes
small, membrane bound sacs that contain enzymes specific for dissolving fats, amino acids, and hydrogen peroxide
Cytoskeleton
Proteins that give cells structural support, anchor organelles & facilitate changes in cellular shape
Microtubules are
Thickest of 3 protein fibers, cylindrical tubes
9 + 2 arrangement
is nine pairs of microtubules that are arranged in a circle with two additional microtubules in the center of the circle.
Microfilaments are
thinner and made of two intertwined protein polymers of actin.
Intermediate filaments consist
of a variety of fibrous protein subunits, coiled into cables.
Extracellular matrix (ECM)
is the environment surrounding cells.
Fibronectin connects to
cell surface receptors, called integrins, that extend through the plasma membrane and into the cytosol.
Cell junctions are
small channels, spaces, or pores so adjacent cells can communicate with one another.
Three main types of junctions are tight junctions, desmosomes, and gap junctions.
Tight junctions can be thought of as a belt;
they are mechanical structures that wrap around the cell to prevent extracellular fluid (ECF) from leaking.
Desmosomes are
also mechanical, and act as snaps, or fasteners, that lock together along the longitudinal edge of the cell.
Gap junctions
are tiny pores or channels that allow for the passage of sugars, ions, and amino acids to flow from cell to cell.
The cell membrane (plasma membrane)
is the outermost constituent of the cell.
In 1972, the fluid-mosaic model of membrane structure was introduced, which proposes
that the membrane is a phospholipid double (bi-layer) in which proteins are either partially or entirely embedded, like tiles in a mosaic picture.
Most of the lipids in the membrane are amphipathic phospholipids which
which self-assemble into a bi-layer with their polar (hydrophilic) heads comprising the inner and outer faces of the membrane and their non-polar (hydrophobic) tails facing each other to form the core of the membrane.
Cholesterol may be present in some membranes,
giving extra strength and flexibility to the membrane.
Proteins are the other major
constituent of membranes and can be present in a variety of ways.
Integral proteins
usually function as membrane channels, signaling receptors, or adhesion points; they span across the lipid bilayer as they simultaneously embed themselves in both the inner and outer membrane of the cell.
Peripheral proteins
can be found embedded in either the inner or outer surfaces of the membrane
Glycoproteins are a group of
proteins that have carbohydrate (sugar) chains attached, most often occurring on protein associated with the cell membrane.
What is the purpose of the nucleoplasm?
Provides a safe place where dna replication and transcription can occur within the nucleus
