Results for "nucleus"

Energy Utilisation in Nucleus

Nucleus

1. Protein Targeting - Nucleus

Chapter 15 - Cell Theory, Prokaryotes, and the Nucleus

Nucleus. DNA and Ribosomes

lecture 2 nucleus structure and function

Nucleus and Cell Cycle

EXTERNAL AND INTERNAL STRUCTURE OF THE BRAIN STEM DR A. A. NWAKANMA THE BRAINSTEM •The brainstem is made up of the medulla oblongata, pons and midbrain •It is stalklike in shape and connects the narrow spinal cord with the expanded forebrain •Occupies the posterior cranial fossa of the skull Loading… FUNCTIONS OF BRAINSTEM •It serves as a conduit for the ascending and descending tracts connecting the spinal cord to the different parts of the higher centers in the forebrain •It contains important reflex centers associated with the control of respiration and CVS. •It is also associated with the control of consciousness •It contains important nuclei of cranial nerves II through XII EXTERNAL FEATURES OF MEDULLA OBLONGATA • The medulla oblongata connects the pons superiorly with the SC inferiorly •The junction of the medulla and SC is at the origin of the anterior and posterior roots of the first cervical nerve which corresponds approximately to the level of the foramen magnum Loading… EXTERNAL FEATURES OF MEDULLA •The medulla oblongata is piriform in shape •It has a broad superior part – open part •And a lower closed part •The central canal of the SC continues upward into the lower half of the medulla •In the upper half of the medulla it expands as the cavity of the fourth ventricle EXTERNAL FEATURES OF MEDULLA •On the ant. Surface of the medulla is the anterior median fissure which is continous inferiorly with the ant. Median fissure of the SC •On each side of the median fissure is a swelling called the pyramid EXTERNAL FEATURES OF MEDULLA •The pyramids are composed of bundles of nerve fibers, corticospinal fibers which originate in large nerve cells in the precentral gyrus of the cerebral cortex •The pyramids tapers inferiorly and majority of the descending fibers cross over to the opposite side forming the decussation of the pyramids here •The ant. External arcuate fibers are a few nerve fibers that emerge from the ant. Median fissure above the decussation and pass laterally over the medulla oblongata to enter the cerebellum EXTERNAL FEATURES OF MEDULLA •Posterolateral to the pyramids are the OLIVES which are oval elevations produced by the underlying inf. Olivary nuclei •In the groove b/w the pyramid and olive emerges the rootlets of the hypoglossal nerve •Post. To the olives are the inf. Cerebellar peduncles which connect the medulla to the cerebellum EXTERNAL FEATURES OF MEDULLA •In the groove b/w the olive and the inf. Cerebellar peduncle emerges the roots of the glossopharyngeal and vagus nerves and the cranial roots of accessory nerve •The post. Surface of the sup. Half of the medulla forms the lower part of the floor of the 4th ventricle External features of medulla •The post surface of the inf. Half continues with the post. Aspect of the SC and possesses a post. Median sulcus •On each side of the median sulcus is an elongated swelling , the Gracile tubercle produced by the underlying gracile nu. •Lat. To the gracile tubercle is the cuneate tubercle produced by the underlying cuneate nu. Loading… INTERNAL STRUCTURE OF MEDULLA •The internal structure of the medulla oblongata is usually considered at 3 levels •Level of pyramidal decussation •Level of olive •Level of sensory or lemniscal decussation T/S OF MEDULLA AT THE LEVEL OF OLIVE •This level corresponds to the floor of the 4th ventricle and the cranial n. Nuclei seen include •Hypoglossal n. • Vestibular nuclei •Dorsal nu. Of vagus •Solitary tract and its nu. •Nu. Ambigus • dorsal and ventral cochlear nu. T/S OF MEDULLA AT THE LEVEL OF OLIVE •The other masses of gray matter seen at this level include •The medial and dorsal accessory olivary nu. •Lat. Reticular nu. •Arcuate nu. •The descending tracts seen include •Pyramid •Rubrospinal tract •Spinal nu. And •Tract of trigeminal n. T/S OF MEDULLA AT THE LEVEL OF OLIVE •The ascending tracts include •Medial lemniscus lying in the middle and is L shaped •Spinothalamic T •Spinocerbellar T. •Spinotectal T. •The reticular formation and the inf. Olivary nu. Are also prominent features found at this level T/S OF THE MEDULLA AT THE LEVEL OF LEMNISCAL DECUSSATION •The level represented by this section lies a little above the level of the pyramidal decussation •The structures found at this level include •Central canal surrounded by gray matter •Medial lemniscus •The pyramids the nu. And fasciculus cuneatus •Spinal nu. Of trigeminal n. •The reticular formation T/S OF THE MEDULLA AT THE LEVEL OF LEMNISCAL DECUSSATION •Internal arcuate fibers which arise from the nu. Gracilis and cuneatus and arch forward on the medial side of the gray matter crossing in the midline to form the lemniscal or sensory decussation •Accessory cuneate nu. Lying dorsolateral to the cuneate nu. T/S OF THE MEDULLA AT THE LEVEL OF LEMNISCAL DECUSSATION •The cranial nerve nuclei seen at this level include •Hypoglossal nu. •Dorsal motor nu. Of vagus •Arcuate nu. •Nu. Of solitary tract •Nu. Ambigus •Other structures include •Lower part of inf. Olivary nu. •Lat. Reticular nu. •Arcuate nu. •Lat. & ventral spinothalamic tr. •Doral and ventral spinocerebella tr. •Spino-olivary tr. •Pyramids •Vestibulospinal tr. •Corticospinal tr. •Medial longitudinal fasciculus Connections of the Inferior Olivary Complex • The main afferents of the inferior olivary nucleus are from the cerebral cortex and from the spinal cord • The main efferents are to the cerebellar cortex. • An olivospinal tract is traditionally described, but some authorities hold that the inferior olivary nuclei do not send any fibres to the spinal cord. •The nucleus may be regarded as a relay station on the cortico-olivo-cerebellar and spino-olivo-cerebellar pathways. • The accessory olivary nuclei are connected to the cerebellum by parolivo-cerebellar fibres. THE PONS •The pons is the middle part of the brainstem •Its continuous below with the medulla oblongata and above with the midbrain •It is seperated from the cerbellum by the 4th ventricle •Pons has two surfaces: •Ventral and dorsal External Features Of Ventral Surface Of Pons •The ventral surface of pons shows the following features •The ventral surface is convex and has a shallow groove in the midline called the basilar groove which lodges basillar artery •Transvesely running fibers connecting the pons to the cerebellum thru the middle cerebellar peduncle •The two roots of trigeminal nerve (sensory and motor) emerge at the jxn b/w the ventral surface of pons and middle cerebellar peduncle EXTERNAL FEATURES OF DORSAL PONS •The dorsal surface of pons shows the following features •Median sulcus in the median plane •Medial eminence – shows rounded elevation in the lower part called facial colliculus which overlies the nu. Of abducent n. •Sulcus limitans – is lat. To the medial eminence and seperates medial eminence from vestibular area T/S THROUGH CAUDAL PART OF PONS •The features seen at this level include •Medial lemniscus in the most ant. Part of the tegmentum •The facial nu. Lies post to the lat. Part of the medial lemniscus •The fibers of the facial nerve wind around the nu. Of the abducent nerve producing the facial colliculus T/S THROUGH CAUDAL PART OF PONS •The medial longitudinal fasciculus is situated beneath the floor of the 4th ventricle on either side of the midline •The medial longitudinal fasciculus is the main pathway that connects the vestibular and cochlear nuclei with the nuclei controlling the extraocular muscles (oculomotor, trochlear and abducent) •The medial vestibular nu. Is situated lat. To the abducent nu. And in close relationship to the inf. Cerebellar peduncle T/S THROUGH CAUDAL PART OF PONS •The sup. Part of the lat. And inf. Part of sup. Vestibular nu. Are found at this level •Post. And ant. Cochlear nu. Are also found at this level •The spinal nu.of trigeminal nerve and tract lie on the anteromedial aspect of the inf. Cerebellar peduncle T/S THROUGH CAUDAL PART OF PONS •The trapezoid body is made up of fibers derived from the cochlear nuclei and the nuclei of trapezoid body •They run transversely in the ant. Part of the tegmentum •The basilar part of the pons at this level contain masses of nervr cells called pontine nuclei T/S THROUGH CAUDAL PART OF PONS •The axons of these cells give origin to the transverse fibers of the pons which cross the midline and intersect the corticospinal and corticonuclear tracts breaking them up into small bundles Loading… INTERNAL STRUCTURE OF CRANIAL PART OF PONS •The internal structure of the cranial part of pons is similar to that seen at the caudal level but contains the motor and principal sensory nuclei of the trigeminal nerve •The motor nu. Of the trigeminal nerve is situated beneath the lat. Part of the 4th ventricle within the reticular formation INTERNAL STRUCTURE OF CRANIAL PART OF PONS •The principal sensory nu. Of the trigeminal nerve is situated lateral to the motor nu. •The sup. Cerebellar peduncle is situated posterolat. To the motor nu. Of trigeminal nerve EXTERNAL FEATURES OF MIDBRAIN •Midbrain measures about 2cm in length and connects the pons and cerebellum with the forebrain •The midbrain is traversed by a narrow channel – the cerebral aqueduct ( which is filled with CSF) •On the posterior surface are four rounded eminences that are divided into superior and inferior pairs •The sup. Colliculi are centers for visual reflexes while the inf. Are lower auditory centers •In the midline below the inf. Colliculi emerges the trochlear nerves EXTERNAL FEATURES OF MIDBRAIN •Each colliculi is related to a ridge called brachium •The sup. Brachium passes from the sup. Colliculus to the lat. Geniculate body and the optic tract •The inf. brachium connects the inf colliculus to the medial geniculate body EXTERNAL FEATURES OF MIDBRAIN •On the anterior aspect of the midbrain is a deep depression in the midline called the interpeduncular fossa which is bounded on either side by the crus cerebri •Many blood vessels perforate the floor of the interpeduncular fossa and this region is termed the post. Perforated substance INTERNAL STRUCTURE OF MIDBRAIN •The midbrain is divided into two parts – •An upper tectum and •A lower part called cerebral peduncles •The upper part (tectum) contains mainly the colliculi of the two sides and represents the dorsal part of the midbrain •The cerebral peduncles are subdivided by the substantia nigra into •The tegmentum and •Crus cerebri STRUCTURE OF MIDBRAIN AT OF INF. COLLICULUS •The structures seen at this level include •Crus cerebri- this contain descending fibers from different parts of the cerebral cortex •The medial 1/6 contain frontopontine fibers •The intemediate 2/3 contain corticospinal and corticonuclear fibers •The lat. 1/6 contain temporopontine fibers •Other structures include •Substantia nigra •Cerebral aqueduct : this is surrounded by the central gray matter. •Ventral to this aqueduct is the oculomotor and trochlear nerves STRUCTURE OF MIDBRAIN AT OF INF. COLLICULUS •Reticular formation b/w the substantia nigra and gray matter •Inferior colliculus •Mesocephalic nu. Of trigeminal nerve •Compact bundle of fibers lies in the tegmentum dorsomedial to the substantia nigra •This bundle consistsof the medial lemniscus, trigeminal lemniscus and spinal lemniscus •Medial longitudinal fasciculus •Superior cerebellar peduncle •Rubrospinal tract Structure of midbrain at the level of sup. colliculus •The following structures are seen at this level •Sup. Colliculus in the tectum •Red nu. In the tegmentum dorsomedial to the substantia nigra •Oculomotor nuclei near the central gray matter •Bundles of ascending fibers consisting of medial lemniscus, spinal lemniscus and trigeminal lemniscus Structure of midbrain at the level of sup. colliculus •Dorsal tegmental decussation : this consists of fibers originating in the sup. Colliculus, it crosses to the opp. Side and descend as the tectospinal tract •Ventral tegmental decussation : this originates in the red nu

Lecture 4 - Nucleus

Nucleus Part 2

Nucleus Part 1

1. Hyperemesis Gravidarum/ Pernicious Vomiting Definition: Excessive nausea and vomiting during pregnancy, extending beyond week 12 or causing dehydration, ketonuria, and significant weight loss within the first 12 weeks. Incidence: 1 in 200-300 women Cause: Unknown, but may be associated with increased thyroid function and Helicobacter pylori infection. Signs and Symptoms: • Decreased urine output • Weight loss • Ketonuria • Dry mucous membranes • Poor skin turgor • Elevated hematocrit • Decreased sodium, potassium, and chloride levels • Polyneuritis (in some cases) Assessment: • Hemoglobin: Elevated hematocrit concentration (hemoconcentration) due to inability to retain fluids. • Electrolytes: Decreased sodium, potassium, and chloride levels due to low intake. • Acid-base Balance: Hypokalemic alkalosis (severe vomiting, prolonged period). • Neurological Examination: Polyneuritis due to B vitamin deficiency. Effects (if left untreated): • Intrauterine Growth Restriction (IUGR): Dehydration and inability to provide nutrients for fetal growth. • Preterm birth: Due to complications caused by the condition. • Prolonged hospitalization/home care: Resulting in social isolation. Therapeutic Management: • Fluid and Electrolyte Management: Monitor input and output, blood chemistry to prevent dehydration. • Nutritional Support: Withhold oral food and fluids (usually) and administer total parenteral nutrition (TPN). • Intravenous Fluid Replacement: 3000 ml Ringer's lactate with added vitamin B to increase hydration. • Antiemetic Medication: Metoclopramide (Reglan) to control vomiting. 2. Ectopic Pregnancy Definition: Implantation of a fertilized egg outside the uterine cavity (ovary, cervix, fallopian tube - most common). Incidence: Second most frequent cause of bleeding during the first trimester. Causes: • Obstruction of the fallopian tube: ◦ Adhesions (from previous infection like chronic salpingitis or pelvic inflammatory disease). ◦ Congenital malformations. ◦ Scars from tubal surgery. ◦ Uterine tumor pressing on the proximal end of the tube. ◦ Current use of an intrauterine device (IUD). Signs and Symptoms: • Missed period/amenorrhea. • Positive hCG test. • Sharp, stabbing pain in the lower abdominal quadrants and pelvic pain (at time of rupture). • Scant vaginal spotting/bleeding. • Rigid abdomen (from peritoneal irritation). • Leukocytosis (increased WBC count due to trauma). • Decreased blood pressure and increased pulse rate (signs of shock). • Cullen's sign (bluish tinge around the umbilicus). • Tender mass palpable in the cul-de-sac of Douglas (vaginal exam). • Falling hCG or serum progesterone level (suggesting the pregnancy has ended). • No gestational sac on ultrasound. Therapeutic Management: • Non-ruptured Ectopic Pregnancy: Oral administration of methotrexate followed by leucovorin. • Ruptured Ectopic Pregnancy (emergency): Laparoscopy to ligate bleeding vessels and remove or repair the damaged fallopian tube. 3. Hydatidiform Mole (H-mole)/ Gestational Trophoblastic Disease/ Molar Pregnancy Definition: A gestational anomaly of the placenta consisting of a bunch of clear vesicles resembling grapes. This neoplasm is formed from the swelling of the chorionic villi, resulting from a fertilized egg whose nucleus is lost, and the sperm nucleus duplicates, producing a diploid number 46XX. Incidence: Approximately 1 in every 1500 pregnancies. Risk Factors: • Low socioeconomic group (decreased protein intake). • Women under 18 or over 35 years old. • Women of Asian heritage. • Receiving clomiphene citrate (Clomid) for induced ovulation. Types of Molar Growth: • Complete/Classic H-mole: All trophoblastic villi swell and become cystic. No embryonic or fetal tissue present. High risk for malignancy. • Partial/Incomplete H-mole: Some of the villi form normally. Presence of fetal or embryonic tissue. Low risk for malignancy. Signs and Symptoms: • Uterus expands faster than normal. • No fetal heart sounds heard. • Serum or urine test for hCG strongly positive. • Early signs of preeclampsia. • Vaginal bleeding (dark-brown spotting or profuse fresh flow). • Discharge of fluid-filled vesicles. Diagnosis: • Ultrasound. • Chest x-ray (lung metastasis). • Amniocentesis (no fluid). • Hysteroscopy (via cervix). Management: • Evacuation of the mole: Dilation and curettage (D&C). • Blood transfusion. • Hysterectomy (in some cases). • Monitoring hCG levels: Every 2 weeks until normal. • Contraception: Reliable method for 12 months to prevent confusion with a new pregnancy. 4. Premature Cervical Dilatation/ Incompetent Cervix Definition: Premature dilation of the cervix, usually occurring around week 20, when the fetus is too immature to survive. Incidence: About 1% of pregnancies. Causes: • Increased maternal age. • Congenital structural defects. • Trauma to the cervix (cone biopsy, repeated D&C). Signs and Symptoms: • Painless dilation of the cervix. • Pink-stained vaginal discharge. • Increased pelvic pressure. • Rupture of membranes and discharge of amniotic fluid. Therapeutic Management: • Cervical cerclage: Surgical procedure to prevent loss of the child due to premature dilation. • Bed rest: After cerclage surgery, to decrease pressure on the sutures. 5. Abortion Definition: Termination of pregnancy before the fetus is viable (400-500 grams or 20-24 weeks gestation). Types of Abortion: • Spontaneous Abortion: Pregnancy interruption due to natural causes. ◦ Threatened: Mild cramping, vaginal spotting. ◦ Inevitable/Imminent: Profuse bleeding, uterine contractions, cervical dilation. ◦ Complete: All products of conception expelled spontaneously. ◦ Incomplete: Part of the conceptus expelled, some retained in the uterus. ◦ Missed: Fetus dies in utero but is not expelled. ◦ Habitual: 3 or more consecutive spontaneous abortions. • Induced Abortion: Deliberate termination of pregnancy in a controlled setting. Complications of Abortion: • Hemorrhage. • Infection (endometritis, parametritis, peritonitis, thrombophlebitis, septicemia). Management: • Bed rest. • Emotional support. • Sedation. • D&C: Surgical removal of retained products of conception. • Antibiotics. • Blood transfusion. 6. Placenta Previa Definition: The placenta is implanted in the lower uterine segment, covering the cervical os, obstructing the birth canal. Incidence: 5 per 1000 pregnancies. Signs and Symptoms: • Abrupt, painless vaginal bleeding (bright red). • Bleeding may stop or slow after the initial hemorrhage, but continue as spotting. Types: • Total: Placenta completely obstructs the cervical os. • Partial: Placenta partially obstructs the cervical os. • Marginal: Placenta edge approaches the cervical os. • Low-lying: Placenta implanted in the lower rather than the upper portion of the uterus. Therapeutic Management: • Immediate Care: Bed rest in a side-lying position. • Assessment: Monitor vital signs, bleeding, and fetal heart sounds. • Intravenous Therapy: Fluid replacement with large gauge catheter. • Delivery: Vaginal birth (safe for infant if previa is less than 30%). Cesarean section (safest for both mother and infant if previa is over 30%). 7. Abruptio Placenta/ Premature Separation of Placenta/ Accidental Hemorrhage/ Placental Abruption Definition: Separation of a normally implanted placenta after the 20th week of pregnancy, before birth of the fetus. Incidence: Most frequent cause of perinatal death. Causes: • Unknown. • Predisposing Factors: ◦ High parity. ◦ Advanced maternal age. ◦ Short umbilical cord. ◦ Chronic hypertensive disease. ◦ PIH. ◦ Trauma (automobile accident, intimate partner abuse). ◦ Cocaine or cigarette use. ◦ Thrombophilitic conditions (autoimmune antibodies). Classification: • Total/Complete: Concealed hemorrhage. • Partial: Concealed or apparent hemorrhage. Signs and Symptoms: • Sharp, stabbing pain in the uterine fundus. • Contractions accompanied by pain. • Uterine tenderness on palpation. • Heavy vaginal bleeding (may be concealed). • Signs of shock. • Tense, rigid uterus. • Disseminated Intravascular Coagulation (DIC). Therapeutic Management: • Fluid Replacement: IV fluids. • Oxygen: Limit fetal hypoxia. • Fetal Monitoring: External fetal heart rate monitoring. • Fibrinogen Determination: IV fibrinogen or cryoprecipitate. • Lateral Position: Prevent pressure on the vena cava. • Delivery: CS is the method of choice if birth is not imminent. 8. Premature Rupture of Membranes Definition: Rupture of the fetal membranes with loss of amniotic fluid during pregnancy before 37 weeks. Incidence: 5%-10% of pregnancies. Causes: • Unknown. • Associated with: Infection of the membranes (chorioamnionitis), vaginal infections (gonorrhea, streptococcus B, Chlamydia). Signs and Symptoms: • Sudden gush of clear fluid from the vagina with continued minimal leakage. • Nitrazine paper test: Amniotic fluid turns the paper blue (alkaline), urine remains yellow (acidic). • Microscopic examination: Amniotic fluid shows ferning, urine does not. • Ultrasound: Assess amniotic fluid index. • Signs of infection (increased WBC count, C-reactive protein, temperature, tenderness, odorous vaginal discharge). Therapeutic Management: • Bed Rest: To prevent further leakage and risk of infection. • Corticosteroids: To hasten fetal lung maturity. • Prophylactic Antibiotics: To reduce risk of infection. • Intravenous Penicillin/Ampicillin: If (+) for streptococcus B. • Induction of Labor: If fetus is mature and labor does not begin within 24 hours. 9. Pregnancy-Induced Hypertension (PIH)/ Toxemia Definition: Vasospasm occurring in both small and large arteries during pregnancy, causing elevated blood pressure, proteinuria, and edema. Incidence: Rarely occurs before 20 weeks of pregnancy. Risk Factors: • Multiple pregnancy. • Primiparas younger than 20 or older than 40. • Low socioeconomic background. • Five or more pregnancies. • Hydramnios. • Underlying diseases (heart disease, diabetes). • Rh incompatibility. • History of H-mole. Categories: • Gestational Hypertension: Blood pressure 140/90 or greater, without proteinuria or edema. • Preeclampsia: Blood pressure 140/90 or greater, with proteinuria and edema. • Eclampsia: Seizures or coma accompanied by preeclampsia. Therapeutic Management: • Preeclampsia: Bed rest, balanced diet, left lateral position. • Severe Preeclampsia: Hospitalization, diazepam, hydralazine, magnesium sulfate. • Eclampsia: Magnesium sulfate, diazepam, oxygen therapy, left lateral position

Cellular Organelles - NUCLEUS AND DNA

240: 15. Nucleus

endomembrane system Semi-autonomous organelles Protein sorting to organelles Systems biology of cells Cell Biology & Cell Theory Cell biology: The study of individual cells and their interactions. Cell Theory (Schleiden & Schwann, with contributions from Virchow): All living organisms are composed of one or more cells. Cells are the smallest units of life. New cells arise only from pre-existing cells through division (e.g., binary fission). Origins of Life: Four Overlapping Stages Stage 1: Formation of Organic Molecules Primitive Earth conditions favored spontaneous organic molecule formation. Hypotheses on the origin of organic molecules: Reducing Atmosphere Hypothesis: Earth's early atmosphere (rich in water vapor) facilitated molecule formation. Stanley Miller’s experiment simulated early conditions, producing amino acids and sugars. Extraterrestrial Hypothesis: Organic carbon (amino acids, nucleic acid bases) may have come from meteorites. Debate exists over survival after intense heating. Deep-Sea Vent Hypothesis: Molecules formed in the temperature gradient between hot vent water & cold ocean water. Supported by experimental evidence. Alkaline hydrothermal vents may have created pH gradients that allowed organic molecule formation. Stage 2: Formation of Polymers Early belief: Prebiotic synthesis of polymers was unlikely in aqueous solutions (water competes with polymerization). Experimental evidence: Clay surfaces facilitated the formation of nucleic acid polymers and polysaccharides. Stage 3: Formation of Boundaries Protobionts: Aggregates of prebiotically produced molecules enclosed by membranes. Characteristics of a protobiont: Boundary separating the internal & external environments. Polymers with information (e.g., genetic material, metabolic instructions). Catalytic functions (enzymatic activities). Self-replication. Liposomes: Vesicles surrounded by lipid bilayers. Can enclose RNA and divide. Stage 4: RNA World Hypothesis RNA was likely the first macromolecule in protobionts due to its ability to: Store information. Self-replicate. Catalyze reactions (ribozymes). Chemical Selection & Evolution: RNA mutations allowed faster replication & self-sufficient nucleotide synthesis. Eventually, RNA world was replaced by the DNA-RNA-protein world due to: DNA providing more stable information storage. Proteins offering greater catalytic efficiency and specialized functions. Microscopy Microscopy Parameters Resolution: Ability to distinguish two adjacent objects. Contrast: Difference between structures (enhanced by special dyes). Magnification: Ratio of image size to actual size. Types of Microscopes Light Microscope: Uses light; resolution = 0.2 micrometers. Electron Microscope: Uses electron beams; resolution = 2 nanometers (100x better than light microscopes). Light Microscopy Subtypes Bright Field: Standard; light passes directly through. Phase Contrast: Amplifies differences in light phase shifts. Differential Interference Contrast (DIC): Enhances contrast for internal structures. Electron Microscopy Subtypes Transmission Electron Microscopy (TEM): Thin slices stained with heavy metals. Some electrons scatter while others pass through to create an image. Scanning Electron Microscopy (SEM): Heavy metal-coated sample. Electron beam scans the surface, producing 3D images. Cell Structure & Function Determined by matter, energy, organization, and information. Genome: The complete set of genetic material. Prokaryotic vs. Eukaryotic Cells Feature Prokaryotic Cells Eukaryotic Cells Nucleus ❌ Absent ✅ Present Membrane-bound organelles ❌ None ✅ Yes Size Small (1-10 µm) Large (10-100 µm) Examples Bacteria, Archaea Plants, Animals, Fungi, Protists Prokaryotic Cell Structure Plasma Membrane: Lipid bilayer barrier. Cytoplasm: Internal fluid. Nucleoid Region: DNA storage (no nucleus). Ribosomes: Protein synthesis. Cell Wall: (Some) Provides structure & protection. Glycocalyx: Protection & hydration. Flagella: Movement. Pili: Attachment. Eukaryotic Cell Structure Nucleus: Contains DNA & controls cell functions. Organelles: Rough ER: Protein synthesis & sorting. Smooth ER: Lipid synthesis, detoxification. Golgi Apparatus: Protein modification & sorting. Mitochondria: ATP production (Powerhouse of the Cell™). Lysosomes: Digestive enzymes for breakdown & recycling. Peroxisomes: Breakdown of harmful substances. Cytoskeleton: Provides structure (microtubules, actin filaments, intermediate filaments). Plasma Membrane: Regulates transport & signaling. Endomembrane System Includes: Nucleus, ER, Golgi apparatus, lysosomes, vacuoles, and plasma membrane. Nuclear Envelope: Double membrane structure. Nuclear pores allow molecule transport. Golgi Apparatus: Modifies & sorts proteins/lipids. Packages proteins into vesicles for secretion (exocytosis). Lysosomes: Contain acid hydrolases for macromolecule breakdown. Perform autophagy (organelle recycling). Semi-Autonomous Organelles Mitochondria Function: ATP production (cellular respiration). Structure: Outer & inner membrane (inner folds = cristae for increased surface area). Mitochondrial matrix houses metabolic enzymes. Chloroplasts (Plants & Algae) Function: Photosynthesis (light energy → chemical energy). Structure: Outer & inner membrane. Thylakoid membrane (site of photosynthesis). Contains chlorophyll. Endosymbiosis Theory Mitochondria & chloroplasts evolved from free-living bacteria that were engulfed by an ancestral eukaryotic cell. Protein Sorting & Cell Organization Co-translational sorting: Proteins destined for ER, Golgi, lysosomes, vacuoles, or secretion. Post-translational sorting: Proteins sent to nucleus, mitochondria, chloroplasts, peroxisomes. Systems Biology Studies how cellular components interact to form a functional system

Histology LEC Cells and Organelles PART 1 Nucleus and it's Components

(6) Nucleus

Protein trafficking (nucleus/cytosol/mitochondria)

26.1 - discovery of nucleus

HOMEOSTASIS Maintaining a stable internal environment respond to stimuli Reacting to changes in the environment reproduce and develop Creating new organisms and growing adapt and evolve Changing over time to better suit the environment INDUCTIVE REASONING Making generalizations based on specific observations DEDUCTIVE REASONING Making specific predictions based on general principles Matter Anything that has mass and takes up space elements Substances that cannot be broken down into simpler substances protons Positively charged particles in the nucleus neutrons Neutral particles in the nucleus electrons Negatively charged particles orbiting the nucleus Atomic Number Number of protons in an atom Isotopes Atoms of the same element with different numbers of neutrons Octet Rule Atoms tend to gain, lose, or share electrons to achieve a full outer shell of 8 electrons molecule Two or more atoms held together by chemical bonds compound A substance consisting of two or more different elements IONIC BONDS Bonds formed by the transfer of electrons COVALENT BONDS Bonds formed by the sharing of electrons reactants Starting materials in a chemical reaction products Ending materials in a chemical reaction WATER solvent Dissolves many substances WATER cohesion & adhesion Water molecules stick to each other and other surfaces WATER high surface tension Water's surface resists being broken WATER high heat capacity Water can absorb a lot of heat without changing temperature WATER heat of vaporization Water requires a lot of energy to evaporate WATER varying density Ice is less dense than liquid water acidic solutions Solutions with a pH below 7 basic solutions Solutions with a pH above 7 pH scale Measures the acidity or basicity of a solution buffers Substances that resist changes in pH Organic Molecules Molecules containing carbon carbon The backbone of organic molecules functional groups Chemical groups attached to carbon that give molecules specific properties Macromolecules Large molecules made up of smaller subunits monomers The individual subunits of a polymer polymers Long chains of monomers Dehydration Synthesis Reaction Joins monomers by removing water Hydrolysis Reaction Breaks polymers by adding water Role of Enzymes Speed up chemical reactions Carbohydrates monosaccharides glucose Simple sugars Carbohydrates disaccharides glycosidic bonds Two monosaccharides joined together Carbohydrates polysaccharides starch glycogen cellulose Many monosaccharides joined together LIPIDS Glycerol & Fatty Acids saturated Fatty acids with no double bonds LIPIDS Glycerol & Fatty Acids unsaturated Fatty acids with double bonds PROTEINS Enzymes Proteins that catalyze chemical reactions PROTEINS amino acids peptide bonds The monomers of proteins, joined together PROTEINS protein structure primary The sequence of amino acids PROTEINS protein structure secondary Local folding patterns (e.g., alpha-helices and beta-sheets) PROTEINS protein structure tertiary The overall 3D shape of a single polypeptide PROTEINS protein structure quaternary The arrangement of multiple polypeptides in a protein conformation The 3D shape of a protein denaturation The unfolding of a protein DNA Deoxyribonucleic acid, the genetic material RNA Ribonucleic acid, involved in protein synthesis ATP Adenosine triphosphate, the energy currency of the cell