GenBio q1 module Cheat Sheet (DRAFT) by Jerstellar

1. All known living things are made up of cells.
2. The cell is a structural and functional unit of all living things.
3. All cells come from pre-ex­isting cells by division.
Additi­onal:
1. All cells contain hereditary inform­ation which is passed from cell to cell
during division.
2. All cells are basically the same in chemical compos­ition.
3. All energy flow of life occurs within cells.

All known life are classified into 3 domains: Archea, Bacteria, Eukarya. The organisms in Archea and Bacteria are prokar­yotes while the organisms in Eukarya have eukaryotic cells.

Prokar­yotic cells - simpler and lack the membra­ne-­bound organelles and nucleus; more primitive than eukary­otes, single­-ce­lled.
Eukaryotic cells - single or multic­elllar

Major Difference in Cell Structure
Eukaryotes store their DNA as chromo­somes within the nucleus but prokar­yotes lack the nucleus. Instead, the majority of their DNA is in the nucleoid. Additional DNA pieces, called plasmids, are shaped like rings and reside outside the nucleoid in the cytoplasm.

Differ­ences in Organi­zation
Eukaryotic cells use a specific cell division process called mitosis, while prokar­yotic cells use binary fission.
-Proka­ryotes create an exact copy of themse­lves; though genetic variance occur through transd­uction, which is when virus transmit plasmid containing DNA to bacterial cells (host).
-Eukar­yotes sexually reproduce through meiosis, which maximizes genetic diversity and minimizes mutation.

Ribosomes - produces protein; attached to rough ER within the cytoplasm. consist of ribosomal RNA (rRNA) and ribosomal protein (Humans and other eukaryotes have 3 rRNA strands, while bacteria have 4 rRNA strands). Prokar­yotes consist of 60% rRNA and 40% protein

+ serves as a line of assembly and starts to “read” the mRNA, identifies the corres­ponding tRNA and binds the amino acid to a binding spot.

+ Svedberg units - defined in a centri­fugal field as the sedime­ntation rate of subunits; when placed in centri­fugal chamber, the time it takes for each subunit to reform. The smaller subunits are forming faster than the bigger ones. (Eukar­yotes: 40s and 60s while Prokar­yotes: 30s and 50s)

Centrioles - helps cell divide or make copies of themse­lves; made up of protein strands called microt­ubules. Involved in the formation of the spindle apparatus which functions during cell division.

+ Microt­ubules - mitotic apparatus during mitosis or meiosis and sometimes get arranged just beneath the plasma membrane to form and bear flagella or cilia in flagel­lated or ciliated cells.

A single centriole forms the anchor point or basal body for each individual cilium or flagellum. Basal bodies direct the formation of cilia and flagella as well.

Cytosk­eleton - network of micros­copic molecular filaments found in the cytoplasm of all nucleated eukaryotic cells. Respon­sible for locomotion and preserving the shape of a cell, chromosome movement during cell division and cytoki­nesis.

Structural components of the cytoplasm that help divide chromo­somes in cell division;
+ Mitotic spindle - array of microt­ubular proteins formed in late G-2 following duplic­ation of the centro­somes.
+ Contra­ctile ring - overla­pping array of actin/­myosin proteins; respon­sible for cytoki­nesis, becomes smaller, finally dissecting the cell’s cytoplasm into two separate domains.

Animal Tissue
Epithelial Tissue - consists of closely packed sheets of cells covering surfaces- including the outside of the body- and cavities of the body wall (outer layer of skin and lining of small intestine).
- Polarized, have a top and bottom face; closely packed and this helps them to serve as barriers to fluid movement and potent­ially harmful microbes.
- Can have distinct arrang­ements: cuboidal for secretion; simple columnar for secretion and active absorp­tion; simple squamous for exchange of material through diffusion; stratified squamous for protec­tion; and pseudo­-st­rat­ified columnar for lining or respir­atory tract usually lined with cilia.

Connective Tissue - made up of cells that are suspended in an extrac­ellular matrix; supports and binds tissues together. Most abundant and widely used; functions as protec­tion.
- Protein fibers such as collagen and fibrin form the matrix in a solid, liquid or jellylike ground material.
+ Loose Connective Tissue - protecting organs and blood vessels and connecting epithelial tissues to the underlying muscles.
+ Dense or Fibrous Connective Tissue - found in tendons and ligaments which connect muscles to bones and connect bones.
+ Adipose Tissue - specia­lized connective tissue like body fat, bone, cartilage, and blood in which the extrac­ellular matrix is liquid called plasma.

Muscle Tissue - contain actin and myosin proteins which allow them to contract.
+ Skeletal Muscle - striated (striped) and attached by tendons to the bones, which helps to regulate movements consci­ously. (In the quads or biceps)
+ Smooth Muscle - not striated and involu­ntary. (In blood vessel walls, digestive tract walls, uterus, urinary bladder, etc.)
+ Cardiac Muscle - striated; individual fibers are bound by structures called interc­alated disks, allowing them to contract synchr­ono­usly. (In the walls of the heart)

Nervous Tissue - collects and transmits inform­ation through detecting stimuli. Has 2 cell types:
+ Neurons or Nerve cells - nervous system’s main functi­oning structure; generates nerve impulses which allow neurons to transmit inform­ation.
+ Glia - promotes neuronal activity.

Plant Tissue
Dermal Tissue - covers and protects the plant and monitors exchange of gases and absorption of water in roots.
+ Stomata - specia­lized pores that allow exchange of gas through cuticular holes.
+ Root hairs - or root epidermal cell extens­ions; increase the root surface area, contri­buting signif­icantly to the absorption of water and minerals.

Vascular Tissue - transports water, minerals, and sugars into different parts of the plant.
+ Xylem Tissue - brings water and nutrients from the roots throughout the plant; plays a role in stem structural support.
+ Phloem Tissue - brings organic compounds from the photos­ynt­hesis site throughout the plant.

Ground Tissue - performs different functions depending on the type and position of the cells in the plant, including:
+ Parenchyma - photos­ynt­hesis in the leaves and storage in the roots.
+ Collen­chyma - adds flexib­ility and support in areas of active growth or young plants.
+ Schler­enchyma - adds rigidity and support in areas where growth has stopped or adult plants.

Apical Modifi­cations - surface or luminal; for secretion, absorp­tion, and movement.
+ Microvilli - or brush/­str­iated border; finger­-like cytopl­asmic extensions of the apical surface which expands surface area that helps in absorp­tion. (Found in absorptive epithe­lia).
+ Cilia - for movement or motility. short hair-like structures or projec­tions; its core is composed of microt­ubules, each cilium is connected to a basal body and extends from the free surface.
+ Flagella - have the same axial structure with cilia but longer; also functions for movement. (Present in the tail of sperma­tozoa).

Basal Modifi­cations - base; for structural support and barrier.
+ Basal Infoldings - support the epithelium and also functions as a passive molecular sieve or ultraf­ilter. (Present in mitoch­ond­ria).

Lateral Modifi­cations - sides of the tissue; provide barrier and cell-cell commun­ica­tion.
+ Tight Junctions - interc­ellular adhesion complexes in epithelia and endothelia that control parace­llular permea­bility (this parace­llular diffusion barrier is semipe­rme­able).
- Form the border between the apical and basola­teral cell surface domains in polarized epithelia and support the mainte­nance of cell polarity by restri­cting interm­ixing of apical and basola­teral transm­embrane compon­ents.
+ Adherence Junctions - element of the cell-cell junction in which cadherin receptors bridge the neighb­oring plasma membranes via their hemophilic reactions.
- The actin filaments which make up zonula adherens maintain integrity of the cell to better bind.

Cell Membrane - select­ively permeable; barrier that separates the cytoplasm from the cell’s outer surrou­ndings, receive and respond to stimuli.
- Made up of 4 different molecules: phosph­olipid, proteins, choles­terol, and carboh­ydr­ates.

Phosph­olipids
+ Phosph­olipid Bilayer - two-layer of phosph­olipid oriented in opposite direction.
+ Phosph­olipid - consists of a glycerol molecule bonded to a phosphate “head” group and two fatty-acid “tails”.
- Has two ends: Phosphate head end which is hydrop­hilic due to its polarity, and a tail end of two chains of fatty acids which is hydrop­hobic.
- It is amphip­hilic or amphipatic since it has both hydrop­hobic and hydrop­hilic proper­ties.
- Two layers of hydrop­hilic head face intrac­ellular and extrac­ellular fluid respec­tively; the hydrop­hobic end is in the middle, allowing the semipe­rmeable membrane to work.

- This means that nonpolar molecules like oxygen gas, carbon dioxide, and lipids can pass freely, while large polar molecules like glucose are hindered.

Membrane Proteins - can further be classified based on location and function.

Based on Location
+ Integral Proteins - or intrinsic proteins are embedded entirely in the lipid bilayer; extends such that each end reaches the inside and outside of the cell respec­tively.
- Cannot easily be removed without the use of strong detergent .
+ Peripheral Proteins - less mobile; attached to either inner or outer layer of the phosph­olipid bilayer.
- They are easily separable from the lipid bilayer without harming it.

Based on Function
+ Ion Channels - very narrow tube-s­haped protein that help establish a tiny pore in the cell membrane (open and close for Na⁺,K⁺, Cl^–, Ca⁺².).
+ Transp­orter or Carrier Proteins - help transport too large molecules such as glucose and amino acids to go through ion channels.
- Enzymes are chemicals that catalyze and causes chemical reactions to occur.
- Receptor Site Proteins help cells commun­icate with their external enviro­nment through the use of hormones, neurot­ran­smi­tters, and other signaling molecules. (Cells can have up to 20).
- Recogn­ition Sites or Cell Identity Markers are glycop­roteins (carbo­hyd­rates attached to proteins); always on the outside surface and recognize foreign cells. (White Blood Cells for ex.)
+ Choles­terol - stable; helps the cell membrane maintain the approp­riate level of fluidity by managing the space between phosph­oli­pids.

*The cell membrane is a fluid mosaic model because the structure of the membrane is flexible and fluid rather than a rigid solid barrier, and it is composed of different parts like a mosaic.

Passive Transport - does not require the cell to exert any of itsenergy to accomplish the movement.
- Involves diffusion; substances simply move from an area of higher concen­tration to an area of lower concen­tra­tion. (Conce­ntr­ation is higher inside the cell).

Factors Affecting Rate of Diffusion
Concen­tration Gradient - Direct propor­tion.
Temper­ature - Direct propor­tion.
Mass of Particles - Inverse propor­tion.
Solvent Properties - Inverse propor­tion; density and viscosity of solvent.

Types of Passive Transport - Simple Diffusion, Facili­tated Diffusion, and Osmosis.
Simple Diffusion - substance moves down its concen­tration gradient without the use of transport proteins. (Lipids and nonpolar molecules pass easily)
Facili­tated Diffusion - materials diffuse across the plasma membrane with the help of membrane proteins.
- With channel proteins, the transm­embrane proteins present in the membrane act like a pore, in which it allows the transport of molecules.
- Molecules bind in carrier proteins which result in some confor­mat­ional changes in the molecules, facili­tating the movement across the membrane in the intrac­ellular space.

Osmosis - water molecules pass in a select­ively permeable membrane; solution with higher concen­tration will attract or absorb the solvent from another solution.
Osmotic Pressure - causes the water to diffuse through select­ively permeable membranes; directly propor­tional to the solute concet­ration.
Isotonic Solution - The concen­tration of solutions inside and outside of the cell is equal, thus the water movement is balanced. (Iso - equal, tonicity - relative concen­tration of solutes in the water inside and outside the cell).
Hypertonic Solution - The solute concen­tration on the outside is higher; causing crenation (water moves out of the cell, causing the cell to shrink and shrivel) of RBC. (Hyper - above).
Hypotonic Solution - the solute concen­tration is lower outside; which causes the cell to burst. (Hypo - under).
- Plants have rigid cell wall so it is ideal for hypotonic solution, causing it to become turgid or swollen.
Turgor pressure - or hydros­tatic pressure is the resulting force of water against the cell wall; prevents the further net intake of water.
Plasmo­lysis - caused by hypertonic solution on plant cell, causing it to be flaccid or limp; can be reversed through deplas­mol­ysis.
Incipient Plasmo­lysis - caused by isotonic solution on plant cell; not turgid nor flaccid causing the greens of the plant to droop. (Incipient - about to be).

Active Transport - uses transport protein to move a substance against its concen­tration gradie­nt—from an area of lower concen­tration to an area of higher concen­tra­tion.
Carrier Proteins:
Uniporters - transport a single type of molecule or ion. (Ca²⁺ ATPase & H⁺ ATPase)
Symporters - transport two molecules or ions in the same direction. (Glucose – Na⁺ ATPase).
Antipo­rters - transport two molecules or ions in the opposite direct­ions.(Na⁺ – K⁺ ATPase & H⁺ – K⁺ ATPase).
Electrical Gradient - Difference in the charge of molecules in the cell.
Membrane Potential - difference in the electrical potential (voltage) across their cell membrane.
- An electrical potential difference is present whenever there is a net separation of charges in space.
Cell membrane - separates negative and positive charges; the inside of the cell is more negative.

Transport Vesicle - small sac that can pinch off or fuse with a cell membrane; used for larger molecules to enter or leave the cell.
Bulk Transport - mode of transport of large quantities of materials and food particles across the membrane. (Endoc­ytosis and Exocyt­osis).
Endocy­tosis - cell membrane engulfs fluids or large molecules to bring them into the cell. The plasma membrane of the cell invagi­nates and pinches off into the cell.
+ Phagoc­ytosis - "cell eating­"; large particles, such as cells or relatively large particles, are taken in by a cell. Single­-celled eukaryotes called amoebas also use phagoc­ytosis to hunt and consume their prey. (Phagein - to eat; cyto - cell).
+ Pinocy­tosis - "cell drinki­ng"; takes in molecules, including water, which the cell needs from the extrac­ellular fluid. It results in a much smaller vesicle than does phagoc­ytosis, and the vesicle does not need to merge with a lysosome.
+ Recept­or-­med­iated endocy­tosis - receptor proteins on the cell surface are used to capture a specific target molecule (mostly in low concen­tra­tion).
- Might bring toxins to the cell (Flu viruses, diphth­eria, and cholera).
Coat Protein - receptor found on the cytopl­asmic side of the pit. (Clathrin)

Exocytosis - materials are transp­orted from the inside to the outside of the cell in membra­ne-­bound vesicles that fuse with the plasma membrane. (Secretion of proteins and neurot­ran­smi­tters).

Gameto­genesis - diploid (2n) cell undergoes a meiotic cell division to become haploid sex cells.
+ Sperma­tog­enesis - production of millions of sperma­tozoa (sperms) each day through meiosis from primordial germ cells.
Divided into two parts:
Sperma­toc­yto­genesis - There are over 1 billion sperma­togonia in male which form the basal layer of the germinal epithelium and catego­rized into two: Type A and Type B sperma­tog­onia.
Type A sperma­tog­onium - undergo mitosis and produces two daughter cells (Type B sperma­tog­onium and primary sperma­toc­yte).
Type B sperma­tog­onium - from Type A and will repeat mitosis.
Primary Sperma­tocyte - undergoes interphase and meiosis I; produces 2 haploid daughter cells (secondary sperma­toc­ytes).
Secondary Sperma­tocyte - undergoes meiosis II; produces 4 haploid daughter cells (sperm­atids).
Spermi­oge­nesis - spermatids move to the lumen (part of the semini­ferous tubule) and undergo differ­ent­iation to become sperm cells.

FSH (Follicle Stimul­ating Hormone) releases Sertoli cells that trigger sperma­tog­enesis; LH (Luten­izing Hormone) releases testos­terone when it reaches the testes.

+ Oogenesis - production of female gametes (ova) within ovaries (sometimes in oviduct).
Oogania - or ovarian stem cells; formed during fetal develo­pment.
- starts when primordial germ cells move to primordial gonad and undergo continuous mitosis.
Primary Oocytes - about 2 million cells that will undergo meiosis I; which are then arrested in prophase I until puberty.

FSH will trigger the contin­uation of division of the primary oocytes. They will then finish meiosis I with 2 unequal size daughter cells: secondary oocyte and first polar body respec­tively. Proges­terone and Estrogen stimulate oogenesis

Secondary Oocyte - meiosis II but get arrested at metaphase II UNLESS fertilized by sperm and will form another polar body.
- Once meiosis II finishes, the mature egg forms an ovum, before joining its nucleus with the sperm's nucleus to form a zygote.
- The first polar body may also undergo meiosis II to form a third polar body when produced together with the secondary oocyte.

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