Biology

Human gene

- 3 200 million nucleotides formed by exons (codify for protein) and introns (transcribed and removed) - Repeated or unique sequence - Guanine and Cytosine are rich in genes, near them and form a barrier - Adenine and Thymine have fewer genes - Chromosome 1 have the highest amount of genes (sex the lowest)

Cell membrane (cell junction)

- Allows organization of cells tissue -Zonular (surrounds periphery - Adherens junction) or Macular (affects specific regions of cell surface - Desmosome, Hemidesmosome, gap junction and tight junction) Types: - Tight junction: Direct contact between cells and seals gap between epithelial cells. It avoid passing between close by cells with transcellular (trough the cell) and paracellular transport and maintain asymmetry - Anchoring junction: Linked to cytoskeleton and includes two anchor proteins (Ca2+ depended): +Cadherins ca2+ depended adhesion molecule responsible for adhesion, embryogenesis and signal transduction (In desmosome and adherens junction) +Integrins ca2+ depended adhesion molecule which interact with actin and intermediate filaments of cytoskeleton and is responsible for cell adhesion, growth, differentiation and shaping the cell (In Focal adhesion and hemidesmosome) - Gap junction: Controlled by CA2+ concentartion (close in case of too much), permability depends on connexins (6 subunits = 1 connexon = 2 channels connected), electrical couplings and metabolic cooperation. Cooridinates heart beating and cardiac concentration and regulates smooth muscles and movements in intestines.

Cell reproduction

- Asexual (mitosis) when daughter cells are genetically identical to prognitor cells - Sexual (meisois) when genomes are mixed from 2 different progenitors

Nucleus during mitosis

- Condensed chromain in chromosome that separate 2 daughter cells and carries gene. Has a different packing and chromatin structure than when in interphase. Chromosomes: - Cylindrical, high grade of chromatin and DNA packaging - Consists of a p (up/short) and q arm (down/long), telomeres (repeated sequence), 2 chromatides (identical), centromeres and kinetochore (specialiced protein in centromere which pulls apart dublicated chromatids) - Can be primary (metachentric (same arm length), submetacentric or acrocentic) or secondary (telocentric/satellites) - Homologous chromosomes are displayed at mitosis in a Karyogram, ordered by size and position - Karyotype are the characterisitc features based on number and apperance to detect abnormalities and mutation. In eukaryotes: diploid (maternal and paternal). Interphase: Extended and coiled as chromatins Prophase: coil up and condense, centrioles divide and move apart Prometaphase: clearly double structure, centrioles reach opposite poles Metaphase: Seen in karyograms as they aline on metaphase plane Anaphase: centromere split and chromosomes migtate to opposite poles and cell starts to elongate Telophase: daughter chromosome arrives at poles and chromosomes forms chromatin again

Rought ER

- Flattened cisternae with ribosomes on the cytoplasmic surface (external layer) which binds to ribophorins. - Contains more proteins and less lipids and cholesterol. - Not present in red blood cells - Abundant in hepatocytes, cells producing antibodies and cells secreting glycoproteins. Function: - Protein synthesis (First step is transcription - how to make a protein, where the cell makes a copy of the DNA (mRNA). The mRNA is translated by the reading ribosome who makes protein out of amino acids together with tRNA who brings the right amino acids to the ribosome. A signal recognition particle (SRP) recognize the signal sequence of the protein and brings it where it needs to go.) - Protein glycosylation (N-linked oligiosaccharides in the N-terminal which was modified in golgi) - Protein storage (proteins are are bound to chaperones, separated and suffer a maturation process)

Peroxisome

- Formed by growth and division of preexisting peroxisome - Proteins are synthesized on free polyribosomes - Contains catalase (breakdown of toxic peroxides) and peroxidase Types: Microperoxisome and peroxisome Function: - Detoxification of molecules in liver and kidney - Oxidation of long chain fatty acids

Lysosome

- Membrane-bound vesicle that comes from Golgi and contains hydrolytic enzymes (acid hydrolase) used for intracellular digestion and synthesis of macromolecules. - Barrier that separates enzymes form the rest of the cell Types according to the degree of maturation: - Primary is recently formed lysosome which forms the secondary ones and induce digestion of nearby molecules - Secondary are large and contain substances that digest. - Residular bodies is stored in cytosol or fuse with cell membrane and contains materials that cant be degraded Types according to function: - Phagolysosome is involved in cell nutrient and digestion of exogen molecules - Autophagolysosome eliminate cell debris and is related to starvation, recycling of cell structures and overdeveloped organelles Function: - Digestion and elimination of damaged organelles - Replacement of macromolecules when they age

Ovum

- Rich in proteins and lipids - Extracellular matrix work as a protection barrier to sperm and protects from mechanical damage - Specialized secretory granules so that only some spermatozoa can fuse with the egg

Nucleus during interphase

- Round shaped, long and large nucleus, condensed chromatin (heterochromatine), replicated and extended chromosome (carry genes), visible nucleolus and located in the center of the cell. Structure: - Nuclear envelope (differentiated portion of RER important in chromosome formation during cell division): Inner (with specific proteins) and outer (ribosomes on cytoplasmic side) nuclear membrane, Perinuclear space, nuclear lamina (protein network inside nucleus, formed by intermediate filaments and interacting with chromatin) and Pore complex (great molecular complex with 50 nucleporins/proteins which allows transcription of large molecules. Transports RNA while large proteins have to go trough specific channels and small molecules trough aq channels) - Nucleoplasm/Karyoplasm (water, proteins, RNA and ions) is a aq nuclear fluid where replication (DNA synthesis) and transcription take place. - Chromatin is a morphological form of DNA (2m with 4 bases (2 purine (adenine and guanine and 2 pyrimidine (cytosine and thyamine) making a DNA double helix) which comes as Euchromatin (light grey, extended chromatin found in spaces between heterochromatine) or heterochromatine (usually closed and condensed, but opens to favor transcription. In contact with nuclear lamina and form dens isolated lumps in nucleoplasm). The more condensed it is, the longer and more compact the fibers are. - Nucleolus consists of Protein, DNA and RNA and has no membrane. There is at least one of them in each cell, but disappears during mitosis (cell cycle) - comes back after (G1)

Cells in adults

- Somatic (forms the whole body) - Germ (gametes (spermatozoa (small and poor in males) or oocyte (large and rich in females, pause in diplotene prophase)) and their diploid precursors cells. Located in gonads (tests and ovaries) and give rise to mature gametes.

Mitochondria

- Specialized membrane-enclosed organelle providing energy (ATP) for cellular activity such as respiration. - Battery of enzymes and coenzymes - Orientation controlled by microtubules so that it is distributed and located where energy is needed - Consists of an outer membrane (many phospholipids and proteins (cytosolic)), inner membrane space (similar to cytosol + enzymes), inner membrane (Manly proteins, boundary- and cristae membranes and passage of electrons), matrix (Ions, molecules (ca, phosphate...), ribosomes, enzymes and mtDNA(only from mother)) and critae (transverse, longitudinal and tubular) - Never formed from the beginning and must duplicate mass and divide during cell division - More than 150 diseases with DNA mutations (severe and rare) which can affect tissues consuming ATP. Can cause poor growth, development delay, loss of vision and muscle contraction. Leigh syndrome, optic neuropathy and Myopathy are some examples. Function: - Metabolic (produce nutrients and energy) - catabolic (oxidation for cell respiration) and formation of precursors - Protein synthesis (1%) where mitochondria process it own DNA and ribosomes to produce protein - Apoptosis (cell death). A cell requires mitochondria activated, but sometimes mitochondria can trigger apoptosis if it has an internal damage.

Protein degredation

- Ubiquitin degrade short-lived and damaged proteins by attaching to one, marking it for degradation. Then it is surrounded by a proteasome (macromolecular structure), and broken into peptides. - Autophagy degrade long-lived and damaged proteins (cheparone-mediate autophagy), big macrostructure (macroautophagy/ micro for smaller materials) and whole organelles to lysosomes. Responsible for aging, cancer, starvation, liver and heart disease, energy metabolism and immune response.

Stages of fertilization

1) Sperm enters corona radiata (innermost layer of cumulus oophorus) thanks to flagellum 2) Sperm binds to zona pellucida and activate acrosomic reaction which breaks down the membrane 3) 1 Sperm fuses with oocyte and release its head into the cytoplasm to form centrosome 4) Cortical granules react with zona pellucida, thickening it and preventing other sperm from entering while spermatozoon enter cytoplasm of oocyte 5) OOCYTE COMPLETES SECOND MEIOTIC DIVISION AND SECOND POLAR BODY 6) Female and male pronucleus joins and becomes a baby (zygote)

Function of cytoskeleton

1. Control position of intracellular structure: Microtubules determines the position of other organelles with their motor protein (ex: During cell division, microtubules from the mitotic spindle are responsible of separating chromosomes into two daughter cells) 2. Control of shape: Microtubules form a network giving the shape to the cell, actin form cell cortex in microvilli (support) and intermediate filament support cell projection 3. Transmembrane control of intracellular organization: extracellular signals acting trough membrane receptors. 4. Cell movements: Sweep (cilia), rotation (flagella), amoeboid and sliding (actin) 5. Muscle contraction - needs calcium and ATP 6. Cell division: Mictrotubules form mitotic spindle and which segregates chromosomes and microfilaments are involved in cytogenesis

Genetic material in cells

1. DNA (nucleotide) synthesis - replication 2. RNA (nucleotide) synthesis - transcription (heterosynthetic) exported by mRNA out of nucleus to cytoplasm (eukaryote) 3. Protein (amino acid) synthesis - translation 4. Function

Stages of mitosis

1. Prophase (chromatin condense forming chromosomes (with sister chromatids held together by cohesin), in the nucleus kinetochore forms and nucleolus disappear. In cytoplasm centrioles starts to separate and mitotic spindle starts to form) 2. Prometaphase (Nuclear envelope breaks, kinetochore microtubules (forming mitotic spindle) invades nuclear space and attach to kinetochore (2 formed on and by the chromosome) and centromeres are moved apart by polar microtubules) 3. Metaphase (chromosomes line up along metaphase plane and is the phase where you can see karyograms. Mitotic spindle is barrel shaped and the microtubules are either astral (left pole, polar/overlap (right pole) or kinetochore) 4. Anaphase (shortest stage where sister chromatids separate (break at center of centromere) to daughter chromosomes which are pulled apart by kinetochore microtubules (degraded after) to each pole and cell starts to elongate) 5. Telophase (Daughter chromosome reach their poles and forms 2 new nuclei and a new nuclear membrane. Cell elongates more and nuclei is reorganized - nucleoli reapers, transcription, kinetochore disappear and chromosomes return to chromatin)

genetic polymorphism

2 or more relatively common forms of a gene (ex: alteration in nr) - Traits under control of multiple alleles - Nucleotide change in DNA - Similar to mutation, but without consequences

Golgi

4-6 cisterhae and tubular connection with a cis- (thin, close to ER) and trans face (exit) which receives lipids and proteins from ER and send them various directions. - Contains more cholesterol and proteins and less lipids. - Transport vesicles to different organelles where the discording coat is removed and their content released - Clathrin, COP 1 (retrograde) and COP 2 (anterograde) coated vesicles which are selective in recognizing the correct target membrane. Specific proteins: - Rab (monomeric GTPase) direct vesicles to specific spots on the membrane and is associated with one or more membrane enclosed organelles. - SNARE catalyze the fusion of vesicles (V-snare) to a membrane and the lipid bilayer (t-snare (target)) and is associated with a particular organelle. Function: - Recycling of the membrane (continous transport and endocytosed vesicles remove older components) - Protein glycosilation (Produce oligosaccharides) - Protein maturation (In trans phase and includes concentration of protein, polypeptide synthesis, phosphorylation and methylation) - Protein secretion (maturation process; exocrine (extracellular matrix) or endocrine (bloodstream)) - Formation of lysosomal enzymes and acrosome in spermatozoa

Eukaryote

A cell that contains a nucleus and membrane bound organelles. In animal, plants and fungi - pluricellular with all the organelles. Larger ribosomes, subunit, rRna and proteins per ribosomal unit than prokaryote. It has many initiation factors and different translation factors. Function: - Survival: Nourishment (biomolecules obtain energy for chemical reactions or to synthesize new structures), Mitochondrial respiratory process (provides energy to the cell), Synthesis (biomolecules repair damaged structure during development) and Recycling (biomolecules are interconverted) - Self - regulation: Homeostasis or equilibrium which activates signal transductive pathways to maintain a constant environment and avoid cell death. - Reproduction: Mitosis (in cell) //Gamete formation (in organisms) Renewal, development and adaption Biomolecules = H20, O2, CO2 and salts (inorganic) and carbs, lipids, proteins and nucleic acid (organic)

Turner Syndrome

A chromosomal disorder in females in which either an X chromosome is missing, making the person XO instead of XX, or part of one X chromosome is deleted.

Klinefelter syndrome

A chromosomal disorder in which males have an extra X chromosome, making them XXY instead of XY.

Downsyndrome

A genetic chromosome 21 disorder (trisomy - extra chromosme) causing developmental and intellectual delays.

Mitosis

A quick and continuous division process with no interruptions where a cell separates chromosomes into 2 identical sets with 2 nuclei. Components: - Chromosomes (condensed and distributed among daughter cells) - Cytoskeleton (form mitotic spindle (microtubules and protein) and contractile rings (actin and myosin which keeps the cell membrane in the center)) - Centrosome (a pair of centrioles and a surrounding matrix which are duplicated in interphase and pulled apart from microtubules (form Mitotic spindle) and connection is destroyed (form Aster) - ER - Golgi - Nuclear envelopes (form vesicles for division)

Gene

A segment of DNA on a chromosome that codes for a specific trait, regulates homeostasis to avoid diseases and maintain vital features. It is responsible for cell function and structure. - In pairs in somatic cells and segregated during formation of sex cells

Locus

A specific place along the length of a chromosome where a given gene is located. *Monomorphic - same allele in all individuals *Dimorphic - 2 different allele genes (mendelian) *Polymorphic - 3 or more different alleles

Virus

A tiny, nonliving cell (but living organism) that invades and then reproduces inside a living cell. Has a geometric structure and either a RNA or DNA (never both).

Prokaryote

A unicellular organism that lacks a nucleus and membrane bound organelles. Bacterial cell with small ribosomes and subunit (site E), fewer rRNA and less protein per ribosome. No cytoskeleton or endo- and exocytosis, but a cell wall. Circular DNA in the cytosol and 1 inititation factor (GAG).

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits.

Mitochondrial disorders

Caused by mutations in mitochondrial DNA (not in the nucleus). Mitochondrial DNA is only passed down by the mother (only one copy of the gene), males can suffer, but not transmit. Deals with energy and metabolism (organs that require more energy). It usually affects all cells in the body, but not always.

meiosis

Cell division for sexual production where a diploid nuclei becomes 4 haploid cells. Makes gametes and spores. First meiotic division: Reductional division with genetic recombination (DNA fragment exchange between homologous chromosomes) where 2 daughter chromosomes are generated and chromosomes are randomly distributed. 1. Prophase 1 - Homologous recombination: Chromosomes thickens and coils into chromosomes held together by cohesin homologous chromosomes pairs up (synapsis) and crossing over: x Leptotone (2 identical sister chromatids form chromosome during condensation, nucleus increase and mitotic spindle starts to form) x Zygotone - chromosomes continue to shorten and thicken and synapsis/bivalent (homologous chromosomes lines up in pair to tetrad chromosomes) in a zipper-like fashion x Pachytene - chromosomes coil and shorten and cross over (segment exchange between non-sisters) x Diplotene - Meiosis may pause as chromosomes separate from each other and synaptonemal comples is degraded (oocytes stop here before birth and continues during puberty) x Diakinesis - Mitotic spindle has formed, nuclear membrane, disintegrates into vesicles and nucleoli disappears. 4 parts of tetrads visible. 2. Prometaphase 1 - Chromosome attach to spindle fibers through kinetochore microtubules, nucleoli and nuclear envelope disappears. 3. Metaphase 1 - Spindle fibers move the chromosomes to metaphase plane. 4. Anaphase 1 - Kinetochore microtubules shorten and chromosomes are pulled apart towards each pole 5. Telophase 1 - Chromosomes (dyads/ half a tetrad) arrives at poles and get surrounded by nuclear envelope and nucleoli returns. Second meiotic division: 2 chromatids are separated to 4 haploid cells. 1. Prophase 2 - New spindle forms around chromosome (dyad) 2. Metaphase 2 - Dyad line up at equatorial plane 3. Anaphase 2 - Chromosomes divide and chromatids are pulled to opposite poles of the cells 4. Telophase 2 - Nuclear envelope forms, cytoplasm divides and chromatids unwind back to chromatin 5. Cytokinesis 2 - 4 haploid cells are produced

organelles in eukaryotic cells

Centrosome - 2 centrioles (9 microtubule triplets) which help to organize the assembly of microtubules and generates mitotic spindle Chloroplast - everything inside the cell membrane. Chromosomes—house cellular DNA and transmit genetic info. Cilia and Flagella— cell surface projection with different movements formed by bundles of microtubules. Cytosol - Fluid within a cell (mostly water) Endoplasmic Reticulum—synthesizes carbohydrates and lipids. Rough ER - Ribosomes involved in protein synthesis. Golgi Apparatus—synthesizes, stores and distributes certain cellular products. Lysosomes—digest worn out cells and breaks down macromolecules. Mitochondria—provide energy for the cell during oxidative metabolism (ATP) Nucleus — controls cell growth and reproduction Nucleolus - produce ribosomes Peroxisomes— Enzymes that detoxify alcohol, form bile acid, and use oxygen to break down fats. Plasma membrane - regulates the exchange of molecules. Ribosomes—responsible for protein production via translation. Vacuoles - Enclosed compratment surrounded by a tonoplast membrane which stores water and waste products.

Cytoskeleton

Complex network of protein filaments (hundreds of protein molecules) that extend trough the cytoplasm. Highly dynamic structure for shaping and division. Form, organization and cell movement. Filaments: - Microtubules (=13 protofilaments) are hollow, straight, polarized and unbranched cylinders from centrioles, made of tubulin (heterodimer) and binds to GTP. Includes Labile (from mitochondria and forms mitotic spindle) and stable (forming complex structures in centrioles and axonema (head) of cilia and flagella) - Microfilaments includes actin (Branched, flexible and thin polymeres which helps form contractile rings during cell division and in the structure of cell junction and microvilli), myosin (2 heavy chains and 2 light chains which binds by their tails to form thick filaments to help movement of cell during cell migration) and sarcomeres (structural and functional units of myofibrils which contracts the skeletal muscles) - Intermediate filaments are thicker than actin and thinner than microtubules which have a structural function and provides mechanical stability to tissues. Different filaments for different cells (keratin, neurofilaments, desmin (smooth and straited muscles), vimentin og laminin (nuclear lamina)) Accessory protein: organize cytoskeleton and is responsible for its structure - motor protein which are either Dynein or Kinesin which bind to polarized filaments and use energy of ATP to move along filaments (produce movement). Head define direction of movement.

Cell membrane

Continuous sheet formed by lipids (phospholipids - bilayer, synthesizes by enzymes and ER of membrane) and proteins (50 times bigger than lipids and involved in structure, recognitions, metabolism and transportation. Synthesized by free ribosomes and RER) which spread over the entire cell surface. Protected from damage by sugars (oligosaccharides - binds lipids and proteins) from the outer surface. - Features include self-healing, fluidity (determined by temp and presence of cholesterol), asymmetry (proteins are different in each side, lipids are different in each monolayer and sugars are only on the external surface) and selective permeability. - Transportation: Passive includes simple diffusion (Hydrophobic molecules (ex: O2, CO2, N2) diffuse lipid bilayer) and facilitated diffusion (H2O and Ions must go trough a fast channel protein (for specific ions) or a slow transport membrane protein (change confirmation to cross)). Active require energy such as an ATP pump, Ion-coupled pumps and macromolecules trough vesicles: + Exocytosis (out) secrete from golgi to cell membrane and is constitutive (continous flow of vesicles leaving golgi) or induced (product is stored in vesicles formed in golgi and discharged into extracellular matrix) + Endocytosis (inn) ingest substances with vesicles from the cell membrane trough phagocytosis (ingestion of large particles which feed unicellurlar organisms and defend multicellular organisms), pinocytosis (ingestion of substances dissolved to a small liquid drop) and trancytosis (receptors transferring specific molecules). -Components: +Microvilli in the apical surface which helps digestion, shape the cytoskeleton, increase absorption rate and cellular surface (3000 microvilli in a cell) +Lateral interdigitation which increase the contact surface among cells +Cell Junctions

cell-cell communication

Extracellular chemical signals that will induce a respond in the receptor cell with intracellular signal pathways (molecule (small peptides and amino acids) - protein (in cell) - protein (outside of cell) - response) Signaling cells: - Endocrine cell release hormones into the bloodstream (slow) - Paracrine cells is wound healing process (short life) - Autocrine cells for embryonic development and used against cancer cells (strong or weak signal) - Neurons (synaptic transmission with neurotransmitters) Surface receptors: Ion channel, G protein and enzyme coupled Intracellular receptors: Nuclear and bound those bound to cytoplasmic enzymes Signaling cascade: Signal receptor - receptor activation - receptor transduction - activation of target cell - cell response

adhesion cell-matrix

Extracellular proteins involved in cell-matrix interaction. Types: -Glycoprotein +Fibronectin (main in connective tissue and connects the components of the matrix with the cell surface. Multiple doimains, involved in blood clotting and can be soluble in plasma or insoluble in matrix) +Lamini (primary organizer of sheet structure in basal lamina. 3 polypeptide chains hold together by disulfide bonds) -Molecules involved in cell junction and found in transmembrane +Ca2+ depended - Cadherins, integrins and selesctins (involved in intracellular adhesion in the bloodstream (binds to oligosaccharides)) +Ca2+ independed - Immunoglobulins (in nervous system, weaker than cadherins and transmitt signals)

Fertilization

Fusion of an egg and sperm cell to from a zygote (new cell). - Oocyte is captured by the uterine tube and transported to uterine tube where they arrive 80 hours later and waits for spermatozoa to fertilize. - Spermatozoa undergo maturation in epididymis (4-12 days) and then mix with vesicles and acids (40-250 million are expelled) during ejaculation (utløsning). They are deposited in upper part of vigina where they meet a mucous plug (ca 1000 get through) and only dozens pass uterus and fallopian tubes.

Cell cycle regulation

Intracellular: require enzymatic control - Cyclins form heterodimers when binding to kinase and activates the cyclin-dependent kinases complex which can cause mutation during mitosis. Cyclins determine progression (DNA replication, mitosis and cytogenesis) when activating/inactivating CDK. - Tumor supressors are genes related to checkpoints - Check point track progression (and prevent it at specific points) and repair DNA Extracellular: growth factors attaching to receptors in PM - Protoncongenes activate genes involved in cell proliferation, but forms oncognesis in case of mutation, which develop tumors (such as cancer)

extracellular matrix

It can be resistant and flexible (dermis), soft and transparent (gelatin in eye), hard (bone) and elastic (cartilage). Functions: - Participate in cell communication - Confer mechanical resistance to the tissue such as compression - Constitute the homeostatic, nutritive and metabolic media - Fill in interstitial space and maintain tissue structure Components: - Ground substance: +Water, solutes (ions and cations) and proteins (globulins) +Glycosaminoglycans (large, non-flexible and unbranched polysaccharides composed of disaccharides. Negatively charged and forms proteoglycans when binding to skeleton) ex: Hyaluronic acid (barrier agains bacteria in dermis and cartilage), keratine- (cartilage and cornea og eye), dermatan- (skin) and condoitin sulphate (in body (bones)). +Proteoglycans (Glycosaminoglycans and a protein) ex: Aggrecan (responsible for viscosity, mechanical support and barrier) - Fiber (collagen and elastin) - Cells such as fibroblast and mastcells

Smooth ER

Lack ribosomes, but contains tubules which allows storage of key enzymes. In cells specialized in lipid metabolism, cells involved in drug detoxifying and muscle cells. Function: - Lipid synthesis: 1. The major classes of lipids, including phospholipids, cholesterol (hepatocytes), lipoproteins and steroid hormones. 2. Phospholipids and cholesterol 3. Newly synthesized phospholipids are added to cytosolic layer and transferred to the lumen half to grow as a lipid bilayer. 4. Cholesterol and lipids from organelles that do not fuse vesicles 5. Steroid hormones are synthesized in mitochondria and end up on SR where enterocytes, chylomicrons (cholesterol transport) are synthesized. - Glycogenesis (storage of glucose and glycogen) and glycogenolysis (hydrolysis to release glucose) - Detoxification (degradation of drugs and harmful content in hepatocytes, liver, kidney, skin and lungs) - Muscle contraction and storage of Ca2+ (released in the response to external stimuli)

Endoplasmic reticulum

Large membrane system or netlike structure of branching tubules that extend trough-out the cytosol. Function: - Renewal or secretion of structures (biosynthesis) in lipids and proteins such as the production of transmembrane. - Store Ca2+ which will be released in cell signal responses such as muscle contraction.

Cell nucleus

Membranous organelle containing genetic material and allows compartalizion of DNA. Contains info to synthesize everything the cell needs and continuously exchange substances and info with cytoplasm. - Contains cell nucleus (region separated form the rest of the component and includes genetic material), nuclear envelope (double nuclear membrane), nucleolus (rRNA synthesis and assembly of ribosomal subunits) Functions: - Container og genetic info (chromatin) - Expression of genetic info (DNA transcription - Replication of genetic info and assemble of ribosomes

Apoptosis

Morphological changes: - Chromatin is condensed and cytoskeleton altered - Mitochondria release molecules to activate apoptosis (Initiator or executioner CASPASE) Stages: 1. Active phase - negative or positive induction 2. Decision phase - signal to mt to commit suicide 3. Executive phase - protein degradation and chromatin breakdown Diseases: - Increased apoptosis where too many cells die (ex: AIDS and neuron degenerating disease - Alzheimers and Parkinson) - Inhibitation of apoptosis where not enough cells die (cancer)

Ribosomes

Non-membrane-bounded organelles where proteins are synthesized and translation take place. Found in cytoplasm, rer and mRNA and consists of 2 subunits and 4 binding sites (small (1 for mRNA) and large (3 for tRNA - A,P and E site). Translation: Initiation, Elongation and Termination

Gametogenesis

Process by which gametes (haploid eggs or sperm cells involved in sexual reproduction to form a diploid genome) are produced through the combination of meiosis and other maturational changes.

Cell death

Regulated by homeostasis and require A,B,C signals for survival, D,E for proliferation and F,G for differentiation, cell dies without. - Pathological (necrosis), morphological changes (ex: ER and mt swelling and osmotic lysis/water enters cell membrane) in injured groups of cells that damage cell membrane. Cell can survive. - Physiological (apoptosis), cell death under normal conditions in multicellular eukaryotes to eliminate unwanted host cells. Also involved in development stage and immune system.

Cell cycle

Sequence of events leading to cell division: Interphase: 3 Stages - The longest phase between 2 cell divisions where the cell grows and DNA is replicated. Checkpoints to arrest the cell in case of damage to repair and avoid tumors or mutation. 1. G1 (6-12 h growth phase where RNA and proteins are synthesized (If not it goes to resting phase (G0) The cell can go to the next stage in case of right size and non-damaged DNA) 2. S (6-8 h DNA replication (chromosome form a sister chromatid) and chromatin decondensation) 3. G2 (3-4 h checkpoint where the cell is growing and RNA and protein is synthesized, centrioles duplicate and cytoskeleton reorganize) 4. M (during mitosis and arrest mitosis if spindle fibers are not properly formed or attachment is inadequate) Cell division: 1. Mitosis - Division of genetic material 2. Cytokinesis - Cytoplasm splits in 2 to make 2 daughter cells (1 nuclei each) which are genetically identical. It happens when contractile ring contracts and begins at the same time as telophase.

Vacuoles

Small membrane-bound organelle with high water content formed by aggregation of small vesicles form Golgi and infolding og PM. Types: - Pulsatile takes water from cytoplasm and throws it outside - Digestive is formed by endocytosis in signal cell organisms Function: - Store waste products and nutrients - Water and gaseous exchange between cell and environment - Regulates density of cytoplasm - Homeostasis maintenance

C-value paradox

The amount of DNA in a reproductive/haploid cell Diploid human genome = 46 chromosomes (22 autosomal and 2 sexual) and Haploid genome = 30 000 genes x 27 000 base paris

Genome

The complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes. In bacteria: - Compact and smaller than eukaryote - 4 million nucleotids (1000 genes) - Operon is clustered genetic regulatory system where genes are close, turned on/off together and become part of a single messenger RNA molecule (translated into individual proteins)

Aging

The process of maturation: Fertilization - embryonic development - give birth - postnatal development - adulthood - senescence - death - Increased probability for death and disease in elderly - Loss of cellular homeostasis - Gather intermediate filaments, waste products and abnormal molecules Possible causes: - Genetic instability, telomere attrition, epigenetic alteration, loss of proteostasis, stem cell exhaustion or deregulated nutrient sensing 1. Free electron in outer layer can cause oxidative damage 2. Mitochondrial theory - antioxidant donate electron to free radical 3. Limited number of cell division - controlled by genetics - Cell divides over time, telomeres shorten and eventually cell division stop.

Spermatognesis

The production of sperm cells/ spermatozoa (small and motile) in seminiferous tubules in testes by spermatogonia (large, round germ cells with homogenous cytoplasm and divided by mitosis to increase number. Supported by sertoli) - Centrioles form flagellum (Tail) where mt is concentrated - Golgi fuse to form acrosome Formation: 74 days - Mature in seminiferous and released in lumen - Transform in primary spermatocyte for 26 days - Meiosis 1 divides spermatocytes to 2 secondary spermatocytes - Meiosis 2 divide spermatocytes to 4 haploids (spermatids - round, polygonal shape and half of genetic material originally in spermatocytes) - Spermiogenesis - spermatid form spermatozoa

Oogenesis

The production, growth, and maturation of an egg, or ovum. In birth we have 500 000 ogonia, in puberty there are 500 left. - Follicle cells surround oocyte and help production of nutrition (Types: Primordial (in new born girls), secondary, tertiary, ovulating and corpus luteum) Process (during fetal development, before birth): - Proliferation period with intense metabolic activity - Growth of primary oocyte right before meiosis - Meiosis 1 paused in diplotene of prophase 1 until puberty - Meiosis 2/ ovulation where cytoplasm divides unequally (ootids gets more than oocytes) and ovum is arrested in metaphase 2 until fertilized by a spermatozoon. In case of no fertilization - corpus luteum

Edwards syndrome

Trisomy 18 associated with rocker-bottom feet, low-set ears, heart disease

Patau Syndrome

Trisomy of chromosome 13