A&P Cell Key terms

Concentration ([ ])

Number of molecules in a given volume

Peripheral proteins

Peripheral proteins in membrane are loosely bound to the surface of the membrane (inside or outside)

Nucleolus

Small, dense body in nucleus, No surrounding membrane where ribosomes are made out of proteins and rRNA

Transcription Elongation

RNA polymerase makes mRNA longer Nucleotides are attached to 3'end of growing mRNA mRNA is complementary to DNA template

rRNA

Ribosomal RNA Important part of the ribosome (structural function)

Genetic code

--Instructions for making proteins --Correspondence of gene and protein sequence --Each of the 20 amino acids is represented in DNA by a particular sequence of 3 nucleotides = codon --Other nucleotide sequences encode instructions for beginning and ending the synthesis of protein• Start codon• Stop codon

Translation

--Making of a specific protein using the mRNA sequence as a templatem --RNA must leave nucleus and associate with a ribosome in cytoplasm --Making proteins is a multi-step process mediated by enzymes --Sequence of bases in mRNA specifies sequence of amino acids of protein --Transfer RNA (tRNA): brings and aligns amino acids anticodon in tRNA connects with codon in mRNA and the right amino acid is placed next to growing polypeptide chain --Amino acids are linked through peptide bonds to form polypeptide

Centrosome

--Organelle composed of two centrioles During the prophase of mitosis, the centrosomes migrate to opposite poles of the cell --The mitotic spindle then forms between the two centrosomes --Upon division, each daughter cell receives one centrosome

Cell cycle

--life of a cell from formation to its own division --Series of changes that it undergoes from the time it forms until it divides --Controlled by checkpoints: Highly regulated --Disruption affects health (delayed wound healing, cancer)

Cleavage furrow

--membrane pinches inward separating newly formed cells --Cleavage furrow is formed from contracting ring of microfilaments and deepens to separate contents into two cells

RNA

-3 types that have different functions (mRNA, tRNA, rRNA) -Nucleotides contain: ribose, phosphate and bases (A,G,U,C) -single chain

Isotonic

-A solution having the same solute concentration as another solution -If cell is in isotonic solution, no net water movement

Interphase

-Before the cell divides, cell must grow and duplicate its contents -great synthetic activity -Cell uses nutrients/fuels to duplicate membranes, organelles and genetic material

Endocytosis

-Bulk transport -Requires energy = active transport -Import (engulfment) of substances useful to the cell from the outside cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane -types: Phagocytosis, Pinocytosis, Receptor-mediated endocytosis

DNA

-Genetic information - instructions to make all possible proteins -Located in the nucleus -Nucleotides contain: deoxyribose, phosphate and bases (A,G,T,C) -Double chain

Integral proteins

-Integral proteins in membrane penetrate the hydrophobic interior of the lipid bilayer = transmembrane proteins -Protein in membrane spans across the bilayerHas hydrophilic and hydrophobic parts *Example: transport molecules, receptors, enzymes, adhesion proteins (e.g. protein that allows attachment to the cytoskeleton and extra-cellular matrix)

Nucleus

-Large, spherical structure, contains genetic material, contains nucleoplasm -contains genetic material controls cellular activities: directs protein synthesis, inheritance (DNA is copied prior to cell division)nuclear envelope = Double-layered, inner and outer lipid bilayer membranes -nuclear pores = protein-lined channels (let molecules in/out of nucleus)

Protein synthesis

-Making of proteins using instructions encoded in the DNA -Happens in cytoplasm (in ribosomes: free or attached to endoplasmic reticulum) -Requires correct amino acids available

mRNA

-Messenger RNA -Carries DNA info to cytoplasm and acts as template for protein -mRNA must leave nucleus and associate with a ribosome in cytoplasm -Has series of codons: each codon is made of 3 bases that code for a specific amino acid

Ion Pumps

-Transport protein that moves ions against their concentration gradient -Needs energy (ATP) -Active transport

Osmosis

-diffusion of water across a selectively permeable membrane, with no expenditure of energy -Membrane must be impermeable to solute -Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration until the solute concentration is equal on both sides -Aquaporin: channel protein in the plasma membrane that specifically facilitates osmosis

Tight junctions

-especially common in epithelial tissue -Specialized proteins form a barrier that is impermeable to the majority of soluble molecules between the two sides of the epithelium

Desmosomes

-especially common in epithelial tissue -specialized adhesive protein complexes that localize to -intercellular junctions and are responsible for maintaining the mechanical integrity of tissues

Centrosome

-microtubules grow out from a centrosome to create the mitotic spindle during cell division = "microtubule-organizing center" -made out of a pair of centrioles microtubules connect with chromosomes and "pull them apart" during cell division

Facilitated diffusion

-passage of a substance across a membrane down its concentration gradient, aided by specific transport proteins, with no expenditure of energy -Usually polar or charged molecules -Without the transport protein (carrier or channel) the membrane is not permeable to substance

Vesicles

-small cellular containers made of membrane -variety of functions: move molecules, secrete substances, digest materials, or regulate pressure in cell

Simple diffusion

-spontaneous movement of particles from where they are more concentrated to where they are less concentrated down the [ ] gradient -Membrane (phospholipid bilayer) is permeable to small non-polar molecules

Phases of Cell Cycle

1. Interphase:• G1 phase: normal cell growth • S phase: copying of chromosomes (DNA replication)• G2 phase: growth in preparation for cell division 2. Mitotic (M) phase: mitosis and cytokinesis

Translation process

1. Ribosome binds mRNA (initiation) 2. 1st tRNA with complementary anticodon holds amino acid in place 3. 2nd tRNA binds to next codon 4. Peptide bond forms between amino acids (making chain) 5. 1st tRNA is released + returns to cytoplasm to be recycled 6. Process repeated as ribosome moves along mRNA (elongation) 7. Amino acids added one at a time to growing protein 8. As the protein molecule forms it folds 9. When the last codon is reached the polypeptide is then released (termination)Process needs energy (GTP)

Codon

3 contiguous bases in mRNA sequence that correspond to a specific anticodon in tRNA and a specific amino acid

Gene expression

A gene that is transcribed and translated is said to be expressed Proteins in a cell determine its function and this can vary with changing conditions - gene expression increases or decreases Gene expression is the basis for cell differentiation (different cells turn on/off different genes and produce different sets of proteins)

Organ system

A group of organs with a common goal (example: digestive system made up of stomach, intestines, pancreas and liver)

Equilibrium

A state of balance. The point at which molecules on one side of a membrane equal molecules on the other side of a membrane

M (mitotic) phase

Actual cell division 2 separate processes• Mitosis: division of nucleus (DNA)• Cytokinesis: division of cytoplasm

Replicated DNA

After S phase Each duplicated chromosome has two identical sister chromatids Sister chromatids are joined Chromatids will separate during cell division

RNA processing

Before mRNA leaves the nucleus addition of a 5' cap and a 3'poly-A tail (RNA splicing

Transcription Initiation

Beginning of transcription transcription factors bind to a specific DNA sequence at the beginning of a gene triggers transcription by RNA polymerase

Somatic cells

Body cells Each cell has 2 copies of each chromosome (one from dad, one from mom)

Exocytosis

Bulk transport Requires energy = active transport Export (secretion) of substances from the inside to the outside of the cell

Mitosis

Cell division in somatic cells Two identical cells arise from one cell

Prophase

Chromatin condenses (gets more compact) Chromosomes made of identical sister chromatids are visible Nuclear envelope and nucleolus break up (disappear) in cytoplasm microtubules assemble from centrosomes to form spindle centrosomes move towards opposite ends (poles) of cell spindle fibers attach to each chromatid

Cilia

Cover free surface of epithelia Many tiny, hair-like structure Move coordinated, beat in succession producing wave of motion that sweeps (move fluids)

Concentration gradient ( [ ])

Difference of the concentration of a solute on both sides of a membrane

Tissues

Different types of cells arranged in a specific way to create specific aggregates that form the structural materials of multi-cellular organism

Plasma membrane

Encloses the cell Phospholipid bilayer (except in archaea: membrane is monolayer with branched hydrocarbon tails) bilayer = stable boundary between two aqueous compartments Components: phospholipids, cholesterol, proteins Fluid-mosaic model: constant sideways movement of molecules; Most lipids and some proteins can shift about laterally; lateral movement of phospholipids is rapid; proteins move more slowly; Some proteins move in a directed manner; others seem to be anchored in place Phospholipids (most abundant lipid in membranes) - molecules with hydrophobic and hydrophilic regions Factors that affect membrane fluidity - As temperatures cool, membranes switch from a fluid state and become more stiff A membrane remains fluid to a lower temperature if it is rich in phospholipids with unsaturated hydrocarbon tails Membranes must be fluid to work properly At warm temperatures (such as 37oC), cholesterol restrains movement of phospholipids; at cool temperatures, it maintains fluidity by preventing tight packing (cholesterol reduces membrane fluidity at moderate temperatures, but at low temperatures hinders solidification)

Intercellular junctions

Extracellular components and connections between cells help coordinate cellular activities Neighboring cells often adhere, interact, communicate by direct physical contact types of intercellular junctions: Tight junctions, Desmosomes, Gap junctions

Cytoplasm

Fills out the cell, contains organelles, space where cell activities occur Liquid part = cytosol = colloid Networks of membranes and organelles suspended in fluid

G1 period (of interphase)

Gap or growth period

G2 period (of interphase)

Gap or growth period, Structures are duplicated

Cytokinesis

Happens during the M (mitotic) phase of cell cycle Continuous process right after mitosis Ring of microfilaments assembles and attaches to inner surface of cell membrane, pinches inward separating newly formed nuclei and distributing about half the organelles into each new cell New cells may differ slightly in size and number of organelles, but contain identical genetic information New cells are ready to enter next interphase

Telophase

Separating chromosomes reach poles Cell continues to elongate Nuclear envelope and nucleoli re-form Chromatin becomes diffuse Spindle disappears

gametes

Sex cells Egg and sperm have only half of the genetic material (one copy of each chromosome)

Hypertonic

In comparing two solutions, the one with the greater concentration of solutesIf cell is in hypertonic solution, water movement OUT OF cell cell gets shriveled

Hypotonic

In comparing two solutions, the one with the lower concentration of solutes If cell is in hypotonic solution, water movement INTO cell cell gets lyzed ("explodes")

Chromosome

Individual molecule of DNA Human cell has 46 chromosomes linear shape (molecule has 2 edges) Visible when they are in condensed (tight) form during cell division

Stages of transcription

Initiation, Elongation, Termination

RNA splicing

Introns (non-coding sequence in mRNA) are cut out Exons (coding sequences in mRNA) are joined together Forms mature mRNA ready to leave the nucleus

Microtubules

Long, slender tubes composed of tubulin, arranged in spiral Thicker than microfilaments Function: cell shape, motility (cilia and flagella), chromosome movement (spindle fibers), organelle movements

Flagella

Longer than ciliaUsually just one (flagellum) Undulating wavelike motion (propeller), example: tail of sperm cell

Chromatin

Loosely coiled fibers of DNA (chromosomes) + proteins (histones) Can have different levels of condensation (loosely tightly packed)

Mitochondria

Major sites of energy production - aerobic cellular respiration (Process to convert chemical energy in lipids and CHOs into ATP) Elongated, fluid-filled sacs that vary in size and shape Move slowly through cytoplasm and reproduce by dividing Contain small amounts of DNA and ribosomes Inner membrane folds extensively (cristae) and contains enzymes for cellular respiration Inner fluid = matrixATP: adenosine triphosphate, energy in a form that can be used during chemical reactions

Transcription

Making a transcript (copy of RNA) of a specific gene Happens in the nucleus Messenger RNA (mRNA) is made by RNA polymerase following rules of complementary base pairing

Membranes

Membranes have distinct inside and outside faces asymmetrical distribution of proteins, lipids, and associated carbohydrates in plasma membrane

Spindle

Microtubules that emerge from the centrosomes and bind to each sister chromatid during prophase The spindle helps the chromosomes meet in the middle during metaphase As the spindle shortens it pulls chromatids apart during anaphase Spindle not attached to chromosomes helps elongate the cell during anaphase Spindle disappears during telophase

Solute

Molecules dissolved in a solvent (liquid) Solvent: Liquid in which molecules are dissolved

Cilia and flagella

Motile extensions from surface of certain cells share a common structure: core of microtubules sheathed by the plasma membrane, basal body that anchors the cilium or flagellum + motor protein called dynein, which drives the bending movements of a cilium or flagellum Differ mainly in length, abundance and motion characteristics

To move down a gradient

Movement from high concentration to low concentration

To move against a gradient

Movement from low concentration to high concentration

Active transport

Movement of particles from where they are less concentrated to where they are more concentrated, against the [ ] gradient with expenditure of energy in the form of ATP Requires a pump *Example: Sodium-potassium pump

Organelles

Structures inside the cell that have a specific cellular function Nucleus, cell membrane, Endoplasmic Reticulum (rough and smooth), Ribosomes, Golgi Apparatus, Mitochondria, Lysosomes and Peroxisomes, Cytoskeleton, Centriole

S phase (of interphase)

Synthesis period with DNA replication

Smooth ER

Synthesizes lipids, metabolizes carbohydrates, Detoxifies drugs and poisons, Stores calcium ions

Tonicity

The ability of a solution to cause a cell within it to gain or lose water

Passive transport

The diffusion of a substance without any input of energy

Microfilaments

Tiny rods of actin that form meshwork or bundles important in movement of the cell and movement of molecules inside the cell Function: cell shape, motility (muscle contraction and cell motion), cytokinesis

Organs

Tissues working together with a common purpose -A part of the body that has a particular function (example: heart, kidney, lung, stomach)

tRNA

Transfer RNA Translates the instructions in mRNA to create a protein Carries specific amino acids to the ribosome Has an anti-codon (region at one end that consists of a particular sequence of 3 bases) that is complementary to a specific codon each tRNA is specific for one type of codon and deliver the corresponding amino acid to the ribosome

Protein channel

Transport protein that allows a specific polar or charged molecules to move across a membrane following its concentration gradient

Carrier protein

Transport protein that changes shape to facilitate the diffusion of a specific molecule(s) across a membrane When it functions against the concentration gradient it is called a pump

Transcription Termination

When RNA polymerase reaches the end of the gene it releases the newly formed mRNA

composite cell

a "universal" cell or a "model" cell, includes all known cell structures (organelles); in reality, a cell has most but not all of these structures (specialized cells differ in number and type of organelles)

Cell division

a way to do exponential growth in cells Cell divides Results in daughter cell IDENTICAL to parent cell Needed for growth of organs/tissues and repair & replacement of cells in an adult organism

cell theory

all living things are composed of cells and all cells come from other cells

Cytoskeleton

cell's internal skeleton framework of thin, threadlike strands in cytoplasm, made of microfilaments, intermediate filaments and microtubules function: Support (cell shape) and motility

Extracellular matrix (ECM)

cells are covered by an elaborate ECM made up of glycoproteins such as collagen, proteoglycans, and fibronectin

Chromosome

chromatin that is packaged into thread-like structures (very compact) before S period of interphase each chromosome has one chromatid after S period of interphase (DNA replication) each chromosome is made of 2 identical sister chromatids held together by the centromere

Lysosomes

digestive compartments within a cell, membranous sac containing digestive enzymes Lysosomal enzymes work best in the acidic environment inside the lysosome function: to digest food and to remove or recycle damaged parts of a cell, damaged organelles

Gap junctions

especially common in epithelial tissue specialized intercellular connection: allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells

Endoplasmic reticulum (ER)

flattened sacs, elongated canals and fluid-filled vesicles, interconnected with cell membrane and nuclear envelope

Golgi Apparatus

flattened sacs, elongated canals and fluid-filled vesicles; one side of Golgi functions as receiving dock for the product and the other as a shipping dock function: finishes, sorts, and ships cell products; functions in conjunction with the ER, modifies products of the ER

Endomembrane system

membranes within a cell, important to connect cell organelles, regulates protein traffic and performs metabolic functions in the cell Network of membranous organelles important for manufacturing products that mostly will end up in the plasma membrane or will be excreted involves the nucleus, nuclear envelope, ribosomes, endoplasmic reticulum, and Golgi

Ribosome

organelle synthesized in the nucleolus (in the nucleus): made of rRNA and 2 protein subunits function: protein synthesis free in cytoplasm vs bound to membrane (RER or nuclear envelope)

Rough ER

outer membrane studded with ribosomes, participates in synthesis of proteins that need further processing or that will be secreted from the cell

Anticodon

region at one end of tRNA that consists of a particular sequence of 3 bases and is complementary to a specific codon

Cell

simplest collection of matter that can live basic unit of life Though cells can differ substantially from one another, they share common features

Peroxisomes

small, membrane-enclosed organelles that contain enzymes involved in a variety of metabolic reactions, including several aspects of energy metabolism. functions: break down fatty acids to be used for forming membranes and as fuel for respiration; and transfer hydrogen from compounds to oxygen to create hydrogen peroxide and then convert hydrogen peroxide into water

Metaphase

spindle fibers attached to each chromatid move chromosomes chromosomes line up midway in the equatorial plate

Anaphase

spindle fibers shorten and pull attached chromatids towards centrosome sister chromatids are pulled apart chromatids separate and become individual chromosomes move in opposite direction guided by microtubules cell elongates

Phases of mitosis

• Prophase • Metaphase • Anaphase • Telophase