Cells Flashcards
Cellular Projections
Not found in all cells, used for movement
Cilia moves materials across the cell surface
Flagellum propels the cell
Phospholipid Structure
A phospholipid molecule consists of a polar phosphate “head”, which is hydrophilic and non-polar lipid “tail”, which is hydrophobic. Unsaturated fatty acids result in kinks in the hydrophobic tails.
Phospholipid Bilayer
The phospholipid bilayer consists of two adjacent sheets of phospholipids, arranged tail to tail. The hydrophobic tails associate with one another, forming the interior of the membrane. The polar heads contact the fluid inside and outside of the cell.
Cell Membrane
The cell membrane of the cell is a phospholipid bilayer containing many different molecular components, including proteins and cholesterol, some with carbohydrates groups attached.
Simple diffusion across the call (plasma) membrane
The structure of the lipid bilayer allows only small non-polar substances such as oxygen and carbon dioxide to pass through the cell membrane, down their concentration gradient, by simple diffusion.
Facilitated Diffusion
Facilitated Diffusion of substances crossing the cell (plasma) membrane takes place with the help of proteins such as channel proteins and carriers proteins. Channel proteins are less selective than carrier proteins, and usually mildly discriminate between their cargo based on size and charge. Carrier proteins are more selective often only allowing one particular type of molecule to cross.
Osmosis
Osmosis is the diffusion of water through a semipermeable membrane down its concentration gradient. If a membrane is permeable to water, though not to a solute, water will equalize its own concentration by diffusion to the side of lower water concentration (and thus the side of higher solute concentration).
Hypertonic
solute concentration higher than another solution
Isotonic
solution has a solute concentration equal to another solution
Hypotonic
a solute concentration lower than another solution
sodium potassium pump
It is found in many cell (plasma) membranes. Powered by ATP, the pomp moves sodium and potassium ions in opposite directions, each against its concentration gradient. In a single cycle of the pump, 3 sodium ions are extruded from and 2 potassium ions are imported into the cell.
3 sodium (NA+): 2 potassium (K+)
endocytosis
Is a form of active transport in which a cell envelopes extracellular materials using its cell membrane.
Phagocytosis
which is relatively nonselective, the cell takes in a large particle
pinocytosis
the cell takes in small particles in fluid.
Receptor- mediated endocytosis
is quite selective, when external receptors bind a specific ligand, the cell responds by endocytosing the ligand
Exocytosis
Endocytosis in reverse. Material destined for export is packaged into a vesicle inside the cell. The membrane of the vesicle fuses with the cell membrane, and the contents are released into the extracellular space.
Smooth ER
synthesizes phospholipids, steroid hormones, regulates the concentration of cellular CA++, metabolizes some carbohydrates, and breaks down certain toxins
Rough ER
studded with numerous ribosomes, which are sites for protein synthesis
Golgi Apparatus
Manipulates products from the rough ER, and also produces new organelles called lysosomes. Proteins and other products of the ER are sent to the Golgi apparatus, which organizes, modifies, packages, and tags them. Some of these products are transported to other areas of the cell and some are exported from the cell through exocytosis.
Mitochondrion
They are the energy- conversion factories of the cell. A mitochondrion is composed of 2 separate lipid bilayer membranes. Along the inner membrane are various molecules that work together to produce ATP, the cell’s major energy currency.
Peroxisome
membrane bound organelles that contain an abundance of enzymes for detoxing harmful substances and lipid metabolism.
3 components of the cytoskeleton
consists of microtubules, microfilaments, and intermediate filaments. The cytoskeleton plays an important role in maintaining cell shape and structure, promoting cellular movement, and aiding cell division.
Nucleus
the control center of the cell, the nucleus of living cells contains the genetic material that determines the entire structure and function of that cell
multinucleate muscle cell
Unlike cardiac muscle cells and smooth muscle cell, which have single nucleus, a skeletal muscle cell contains many nuclei, and is referred to as “multinucleated”. These muscle cells are long and fibrous (often referred to as muscle fibers). During development, many smaller cells fuse to form a mature muscle fiber. The nuclei of the fused cells are conserved in the mature cell, thus imparting a multinucleated characteristic to mature muscle cells.
Red blood cells extruding its nucleus
Mature red blood cells lack a nucleus. As they mature, erythroblasts extrude nucleus, making room from more hemoglobin.
DNA macrostructure
stands of DNA are wrapped around supporting histones. These proteins are increasingly bundles and condensed into chromatin, which is packed tightly into chromosomes when the cell is ready to divide.
Molecular structure of DNA
the double helix is composed of 2 complementary stands. The strands are bonded together via their nitrogenous base pairs using hydrogen bonds.
DNA replication
DNA replication faithfully duplicates the entire genome of the cell. During DNA replication, a number of different enzymes work together to pull apart the 2 strands so each strand can be used as a template to synthesize new complementary strands. The 2 new daughter DNA molecules each contain one preexisting strand and one newly synthesized strand. Thus, DNA replication is said to be “semiconservative”.
The Genetic code
DNA holds all of the genetic information necessary to build a cell’s proteins. The nucleotide sequence of a gene is ultimately translated into an amino acid sequence of the gene’s corresponding protein.
Transcription
DNA to complementary mRNA
Splicing DNA
In the nucleus, a structure called a spliceosome cuts out introns (noncoding regions) within a pre-mRNA transcript and reconnects the exons.
Translation
RNA to protein, the mRNA transcript is “read” by a functional complex consisting of the ribosome and tRNA molecules. tRNA brings the appropriate amino acids in sequence to the growing polypeptide chain by matching their anti- codons with codons on the mRNA strand.
From DNA to protein: Transcription through translation
Transcription within the cell nucleus produces an mRNA molecule, which is modified and then sent into the cytoplasm for translation. The transcript is decoded into a protein with the help of a ribosome and tRNA molecule.
Cell cycle
2 major phases of the cell cycle include mitosis (cell division), and interphase when the cell grows and performs all of its normal functions. Interphase is further subdivided into G1, S, and G2 phases.
