Results for "Interphase"

03. Interphase

biology 2.1Unit 2.1: Mitosis and Meiosis Introduction By the end of this section, you should be able to: Define a chromosome. Define DNA as the genetic material. Define genes. Describe the structure of chromosomes. Describe the components of DNA. Define mitosis and describe its stages. Define meiosis and describe its stages. Relate the events of meiosis to the formation of sex cells. Compare mitosis and meiosis. Chromosomes, Genes, and DNA Almost all the cells of your body—except for mature red blood cells—contain a nucleus, which acts as the control center of the cell. The nucleus holds all the information needed to make a new cell and, ultimately, a new individual. Inside the nucleus are chromosomes, thread-like structures that store genetic information passed from parents to offspring. Chromosomes are made up of DNA (deoxyribonucleic acid), a molecule that carries the instructions needed to make all the proteins in your body. Many of these proteins are enzymes, which control the production of other chemicals and affect everything about how your body functions. Each species has a specific number of chromosomes: Humans have 46 chromosomes (23 pairs). Tomatoes have 24 chromosomes (12 pairs). Elephants have 56 chromosomes (28 pairs). Half of your chromosomes come from your mother, and the other half from your father. These chromosomes are arranged in homologous pairs, meaning they contain matching sets of genes. A karyotype is a special photograph that arranges chromosomes into their pairs. In humans, 22 pairs of chromosomes are called autosomes, which control most body functions. The 23rd pair is the sex chromosomes, which determine whether you are male or female: Females have two X chromosomes (XX). Males have one X and one Y chromosome (XY). DNA Structure DNA is a long, twisted molecule shaped like a double helix (a spiraled ladder). Each strand of DNA is made up of smaller molecules called nucleotides, which consist of: A phosphate group A sugar (deoxyribose) A nitrogen base The four nitrogen bases in DNA are: Adenine (A) → Always pairs with Thymine (T) Cytosine (C) → Always pairs with Guanine (G) Genes are small segments of DNA that carry instructions for making proteins. The sequence of these bases acts like a biological code, directing the cell to create specific proteins. In 1953, James Watson and Francis Crick, using data from Rosalind Franklin’s X-ray photographs, discovered the double-helix structure of DNA. Their discovery led to a huge increase in genetic research, including the Human Genome Project, which mapped all human genes. Mitosis (Cell Division for Growth and Repair) All body cells (somatic cells) divide using mitosis, a type of cell division that creates two identical daughter cells. Mitosis is essential for: Growth (producing new cells). Tissue repair (replacing damaged or old cells). Asexual reproduction (producing offspring with identical DNA). Stages of Mitosis Interphase The cell prepares for division by copying its DNA. Chromosomes are not visible under a microscope. Prophase Chromosomes condense and become visible. The nuclear membrane breaks down. Metaphase Chromosomes line up in the center of the cell. Spindle fibers attach to each chromosome. Anaphase The spindle fibers pull the sister chromatids apart to opposite ends of the cell. Telophase A new nuclear membrane forms around each set of chromosomes. The cell is almost ready to split. Cytokinesis The cytoplasm divides, forming two identical daughter cells. Mitosis is constantly occurring in areas like your skin and bone marrow, where new cells are needed regularly. Meiosis (Cell Division for Reproduction) Unlike mitosis, meiosis occurs only in the reproductive organs (testes in males, ovaries in females) and produces gametes (sperm and egg cells). Gametes have half the number of chromosomes (haploid, n=23) so that when fertilization occurs, the new cell has the correct chromosome number (diploid, 2n=46). Stages of Meiosis Meiosis consists of two rounds of cell division, resulting in four non-identical cells. Meiosis I: Prophase I – Chromosomes pair up and exchange genetic material (crossing over). Metaphase I – Chromosome pairs line up in the center of the cell. Anaphase I – Chromosome pairs separate and move to opposite ends of the cell. Telophase I & Cytokinesis – The cell splits into two haploid daughter cells. Meiosis II (similar to mitosis): 5. Prophase II – Chromosomes condense again. 6. Metaphase II – Chromosomes line up in the center. 7. Anaphase II – Sister chromatids separate and move to opposite sides. 8. Telophase II & Cytokinesis – Four unique haploid gametes are formed. Each gamete is genetically different due to crossing over and random chromosome distribution. Mitosis vs. Meiosis: Key Differences Importance of Mitosis and Meiosis Mitosis ensures that cells grow, repair damage, and replace old cells. Meiosis allows genetic diversity, which is essential for evolution and survival. Summary Chromosomes carry genetic information in the form of DNA. Genes are sections of DNA that code for proteins. Mitosis produces two identical daughter cells for growth and repair. Meiosis creates four non-identical sex cells for reproduction. Mitosis ensures genetic stability, while meiosis introduces genetic diversity

Know the relationship between molecular weight and rate of diffusion The rate of diffusion is inversely proportional to the molecular weight Small weight-fast diffusion; heavy weight-slow diffusion Identify RBC’s in various solution and determine tonicity Tonicity - the ability of an extracellular solution to make water move into or out of a cell by osmosis If a cell is placed in a hypertonic solution, there will be a net flow of water out of the cell, and the cell will lose volume (shrink). A solution will be hypertonic to a cell if its solute concentration is higher than that inside the cell, and the solutes cannot cross the membrane. If a cell is placed in a hypotonic solution, there will be a net flow of water into the cell, the cell will gain volume (bigger). If the solute concentration outside the cell is lower than inside the cell, then solutes cannot cross the membrane, then the solution is hypotonic to the cell. If a cell is placed in an isotonic solution, there will be no set flow of water into or out of the cell, and the cell’s volume will remain stable. If the solute concentration outside the cell is the same as inside the cell, and the solutes cannot cross the membrane, the solution is isotonic to the cell. Homeostatic feedback loop for respiratory rate, heart rate and temperature Respiratory Rate: Stimulus : The level of carbon dioxide (CO2) in the blood increases (often due to exercise or hypoventilation) . Receptors: Chemoreceptors in the medulla oblongata, carotid arteries, and aortic arch detect changes in blood pH and CO2 levels Control Center: The medulla oblongata processes this information Effectors: Respiratory muscles (diaphragm and intercostal) adjust breathing rate and depth Response: Increased respiratory rate removes CO2 and increases O2 intake, restoring normal pH and gas levels. Heart Rate: Stimulus : Changes in blood pressure, O2, CO2, or pH levels Receptors: Baroreceptors (detect blood pressure changes) in the carotid sinus and aortic arch; chemoreceptors monitor blood chemistry Control Center: The medulla oblongata (cardiac center) processes signals Effectors : The autonomic nervous system (ANS) adjusts heart rate through the sympathetic nervous system (increases heart rate) or parasympathetic nervous system (decreases heart rate) Response : Heart rate increases during low O2 or low blood pressure (to circulate oxygen) and decreases when homeostasis is restored. Temperature Regulation Stimulus: Changes in body temperature (hyperthermia or hypothermia) Receptors: Thermoreceptors in the skin and hypothalamus detect temperature fluctuations. Control Center: The hypothalamus processes this information and signals effectors Effectors and Responses: If too hot: Blood vessels dilate (vasodilation) to release heat, and sweat glands produce sweat for cooling If too cold: Blood vessels constrict (vasoconstriction) to retain heat, and shivering generates warmth. Steps of a generic homeostatic feedback loop Stimulus : A change in the internal or external environment that disrupts homeostasis (eg. temperature change, pH levels, blood sugar levels) Sensor (Receptor) : Specialized cells or receptors detect the change and send information to the control center. Control Center (Integrator): Often the brain or endocrine glands, this component processes the information from the sensors and determines the appropriate response to restore balance. Effector: This component carries out the response to the stimulus as dictated by the control center. Effectors can be muscles or glands that help to counteract the change. Response: The action taken by the effectors to restore homeostasis. This could involve increasing or decreasing a physiological process (e.g. sweating to cool down or shivering to warm up) Feedback: The results of the response are monitored. If homeostasis is restored, the system maintains its state; if not, the loop may repeat, continuing to adjust until balance is achieved. How to evaluate data to determine the set point, error, and disturbance Identify the set point The set point is the optimal level or range that the system aims to maintain. To determine the set point: Gather baseline data: Collect data over a period to understand the normal range for the variable in question (e.g. body temp., BP, blood glucose levels) Analyze Trends: Look for patterns in the data to identify the average or median value that represents the stable condition of the system. Consult Literature: Reference established physiological norms or previous studies to confirm the typical set point for the variable. Assess Disturbance A disturbance is any factor or event that causes a deviation from the set point. To evaluate disturbances: Identify External and Internal Factors: Analyze the data for any external influences (e.g. environmental changes, dietary habits) or internal changes (e.g. illness, stress) that might have impacted the variable. Quantity Disturbance: Measure the magnitude and duration of the disturbance. This can be done by comparing the data points during the disturbance against the established set point. Monitor Changes: Track how the system responds to disturbances over time to assess their impact on maintaining homeostasis. WBC types and normal distribution values/ abnormal values and what those values indicate (infections/diseases) (Never Let Monkeys Eat Bananas) Neutrophils (50-70%) - First responders to infections, especially bacterial. High levels indicate bacterial infections, inflammation, or stress. Low levels can indicate bone marrow disorders or severe infections. Lymphocytes (20-40%) - Include B cells and T cells, important for immunity. High levels can suggest viral infections or leukemia, while low levels might indicate immune deficiency. Monocytes (2-8%) - Help with cleaning up dead cells and fighting infections. High levels can be linked to chronic infections or autoimmune diseases. Eosinophils (1-4%) - Involved in allergic reactions and fighting parasites. Elevated levels may indicate allergies or parasitic infections. Basophils (0.5-1%) - Release histamine during allergic reactions. High levels might be see in allergic conditions or blood disorders. Normal WBC Count Total WBC Count: 4000-11000 cells per microliter of blood (varies slightly by lab) Leukocytosis (High WBC): Can indicate infection, inflammation, stress, or leukemia Leukopenia (Low WBC): Can result from bone marrow disorders, viral infections, or autoimmune diseases Neutrophils: Banded vs Segmented Neutrophils are the most abundant type of white blood cells and play a crucial role in fighting infections. They exist in different stages of maturation: Banded Neutrophils (“Bands”) - Immature Neutrophils Appearance: Have a curved, unsegmented nucleus (band-shaped) Normal Range: 0-6% of total WBC count (~0-700/uL) Clinical Significance: Increased Bands (Bandemia) -> Indicates an acute bacterial infection or severe stress (e.g. sepsis). The bone marrow releases immature neutrophils in response to infection. Low Bands -> Not clinically significant unless the total WBC count is low, which could suggest bone marrow suppression. Segmented Neutrophils (“Segs”) - Mature Neutrophils Appearance: Have a segmented nucleus with 2-5 lobes Normal Range: 50-70% of total WBC count (~2500-7000/uL) Clinical Significance: High Segs (Neutrophilia) -> Suggests bacterial infections, stress, chronic inflammation, or leukemia Low Segs (Neutropenia) ->Can be caused by viral infections, bone marrow disorders, chemotherapy, or autoimmune diseases. Discuss the stages of cell cycle/mitosis-which stages are longest/shortest The cell cycle is a series of events that cells go through to grow and divide. It consists of two main phases: Interphase (Longest Phase) – Preparation for division Mitosis (Shortest Phase) – Actual cell division Stages of the Cell Cycle Interphase (90% of the Cell Cycle – Longest Phase) Interphase is the period of cell growth and DNA replication. It has three subphases: G1 Phase (Gap 1) The cell grows, produces proteins, and prepares for DNA replication. Longest variable phase; some cells may stay here indefinitely (e.g., neurons in G0 phase). S Phase (Synthesis) DNA replication occurs, ensuring each daughter cell gets a complete genome. Takes about 6-8 hours in human cells. G2 Phase (Gap 2) The cell prepares for mitosis by producing proteins and organelles. Shorter than G1 but still significant in length. Mitosis: Prophase, Metaphase, Anaphase, Telophase Know proportional and inversely proportional relationships Direct (Proportional) Relationship When two quantities increase or decrease together at a constant rate, they are directly proportional. Inversely Proportional When one variable increases, the other decreases proportionally. Know relationship between molecular weight and rate of diffusion The rate of diffusion of a substance is inversely proportional to the square root of its molecular weight. Lighter molecules diffuse faster Heavier molecules diffuse slower due to greater mass. Know relationship between filtration rate and pressure of fluid or weight of fluid Filtration rate is directly proportional to the pressure or weight of the fluid driving the filtration process. Higher pressure → Higher filtration rate Lower pressure → Lower filtration rate Know why men and women blood values are different The differences in blood values between men and women are due to biological, hormonal, and physiological factors

Interphase | Cells | MCAT | Khan Academy

You place a RBC (0.9%) into a 5% sugar solution. Which statement below is false? The RBC is hypotonic to the 5% solution Which is an example of a sensor in a negative homeostatic feedback loop? Chemoreceptor in carotid body For membrane fluidity experiment, the part of the experiment that actually validated that the membrane was fluid was: The labeled antibodies of the human and mouse intermixing An example of primary active transport would be a protein requiring ATP to transport sodium ions across the plasma membrane. True If a red blood cell is put in a solution and it hemolyzes, then the solution is considered to be: Hypotonic If your body temperature goes too high you can denature enzymes in your body. True What does an integrator do in a homeostatic pathway? Measures the signal coming in to a set point and send a signal out to the body Which of the following represents stages of the cell division (mitosis) in the proper sequence? Prophase, metaphase, anaphase, telophase Which is not true for proteins? They are comprised of mostly cellulose What would be a disturbance for blood glucose homeostasis (normal blood glucose set point = 77mg/dL)? A permanent decrease in insulin production from the Islets of Langerhans Dr. Bio measures your total cholesterol and he reports back to you that your level is 300 mg/ 100 ml of plasma. You do what? Eat more oatmeal and flax to increase your HDL level. How do you make an unsaturated fatty acid? Perform a dehydration synthesis reaction on a saturated fatty acid Which is false for antioxidants? They speed up reactions in your body Which molecules do not dissolve in water? Non-polar Which molecule requires a transport protein to get through the plasma membrane (either channel or carrier protein)? Two of the answers are correct Interphase is considered to be part of normal cell division (mitosis). False What is the function of ATP? All of the answers are correct What are the three kinds of lipids? Triglycerides, phospholipids, and steroids When glycerol combines with 3 fatty acids to form a triglyceride (fat), which of the following chemical reactions has occurred? Dehydration Synthesis How can you alter a protein’s shape? More than one answer is correct If a red blood cell is put into a solution and it maintains its shape, then the solution is considered to be: Isotonic Which molecule requires some type of transport protein to get through the plasma membrane? Sodium Ion Cofactors are molecules that activate enzymes. Which is not a cofactor? Mercury The nitrogenous bases found in DNA have complementary paring. Which pair is correct? C-G Which is not true for meiosis? Results in a gamete that is 2N In the diagram below the two solutions are separated by a semi permeable membrane. In which direction will net movement of water occur? From side A to side B Which is not a component of a DNA molecule: Ribose Sugar Phospholipids are similar to fatty acids except for? Phospholipids have a phosphate group Which is not true for cells? They allow diffusion of all molecules If you combine a molecule of glucose and fructose, which statement is true? You have formed sucrose Which is true for enzymes? Activity will increase until the enzyme becomes saturated What method would you use to get glucose into a cell along/down it’s concentration gradient (from high to low)? Facilitated Diffusion Which is not considered an integrator in a negative homeostatic feedback loop? Pancreas Which phase of the cell cycle is where cytokinesis takes place? Telophase What vitamin do we produce by sitting in the sun; it aids in calcium absorption from the small intestine? Vitamin D Why is it important to think about ion dissociation in the body? All the above In what order do you use macromolecules for fuel? Carbohydrates, lipids, proteins Which is false for cholesterol? It can dissolve in water/blood You place a RBC (0.9%) into a 0.5% sugar solution. Which statement below is false? The RBC is hypertonic to the 0.5% solution Which is not a membrane protein function? Protein synthesis Ingesting (eating) excess hydrophilic vitamins, such as vitamin C, results in excess vitamin C being stored in your tissues. False Diffusion is: The movement of molecules from an area of high molecular concentration to an area of low molecular concentration across a selectively-permeable membrane The hormone responsible for glucose uptake/removal from the blood is: Insulin What method would you use to get sodium ions into a cell against sodium’s concentration gradient (from low to high concentration)? Active Transport Which phase of the cell cycle is where the cell is functioning normally or doing its job? Interphase Evidence for mitochondria once being bacteria that our cells engulfed is: It has it’s own DNA Ionic molecules (ie NA+, K+) can diffuse straight through the plasma membrane. True What is the difference between cis and trans fatty acids? Cis fatty acids have hydrogens on the same side of the carbon double bond and trans fatty acids do not Cofactors are molecules that activate enzymes. Where do we get cofactors from? Vitamins found in fruits and vegetables RNA has what nitrogenous base in place of thymine? Uracil Large polar molecules (ie glucose) can diffuse straight through the plasma membrane? False Which lipoprotein is comprised of more protein and less cholesterol so it scavenges for cholesterol in the blood? High density lipoprotein A normal human being has 46 chromosomes (23 pairs/2N/diploid) in each somatic cell (body cell). True The three main compounds digested by the digestive system are? Fats, carbohydrates, and proteins Meiosis is the process in which our sex cells go from 46 chromosomes to 23 single chromosomes. True The effector in any negative feedback loop is usually: An organ/tissue If a red blood cell is put into a solution and it crenates (shrinks), then the solution is considered to be: Hypertonic Which statement is false for glycogen? It is a disaccharide Enzymes aid in digestion by? Lowering the energy required to break food apart Nonpolar molecules (ie CO2) can diffuse straight through the plasma membrane

Interphase

STRATEGIC PLANNING - Determination of the overall organizational purpose and goals and how they are to be achieved. - HR is the integral component of a strategic plan, greatly affects productivity and organization performance. REQUIREMENT - Forecasting human requirements involves determining the number and types of employees needed. - Level of skills has to be determined and matched with the plan operations. INTERNAL - existing manpower that could be re-assigned or be promoted. EXTERNAL - positions that are not available inside the organization and need to be sourced out. AVAILABILITY - When employee requirement have been analyzed, the firm determines whether there is a surplus or shortage of manpower. SKILL INVENTORY - This approach involves the listing of all the skills possessed by the workforce and they are made to relate to the requirements of the organization. RATIO ANALYSIS - This is a technique wherein the personnel who are promotable to the higher positions are identified together with their backup or understudy. CASCADE APPROACH - Under this approach, the setting of objectives flows from the top to bottom in the organization so that everyone gets a chance to make his contribution. REPLACEMENT APPROACH - Under this approach, HRP is done to have a body of manpower in the organization that is ready to take over existing jobs on a one to one basis within the organization. COMMITMENT PLANNING APPROACH - This involves the supervisors and personnel in every component of the organization on the identification of manpower needs in terms, skills, replacements, policy, working conditions and promotion. SUCCESOR PLANNING APPROACH - The approach known as successor planning takes into consideration the different components of the old plan and increase them. OVER PLANNING - A plan is likely to fail through an inherent weakness of having covered too many aspects of personnel management at the very early stage of HRP in the firm or government office. TECHNIQUE OVERLOAD - The use of many techniques sometimes leads to the gathering of so much information. BIAS FOR THE QUANTITATIVE - There are planners in HRP who sometimes make the mistake of being drawn towards emphasizing the quantitative aspects of personnel management to the neglect of qualitative side. ISOLATION OF THE PLANNERS - When the top management has a low regard for human resource activities and for the HR staff, they give little encouragement to HRP activities, ignore the plan and withdrawn support for plan implementation. ISOLATION FROM ORGANIZATIONAL OBJECTIVES - When HRP is pursued for its own sake or for narrow viewpoint of concentrating on HRD, the effort leads to the formulation of a plan that does not interphase with organizational development. LACK OF LINE SUPERVISOR’S INPUTS LONG TERM FORECASTING - Usually done five years or more. CYCLICAL VARIATIONS - reasonable and predictable movement that occur over a period of one year or more. SEASONAL VARIATIONS - prediction will change over a period of one year. RANDOM VARIATIONS - there is no special pattern and it is difficult to predict or determine. RECRUITMENT - the process of attracting the best individuals to join the company on a timely basis in sufficient numbers and meeting the qualification requirements, thereby encouraging them to apply for the jobs in the organizations. SELECTION - The process of determining from among the applicants who can meet the job requirements and can be offered the vacant position in the organization. JOB DESCRIPTIONS - are written summaries of various jobs consisting of duties, responsibilities and qualifications. JOB SPECIFICATION - refers to the minimum qualifications required by a particular job such as educational background, experience, skills and abilities. STRUCTURE INTERVIEW - follows set of procedures UNSTRUCTURED INTERVIEW - applicant takes the lead. PANEL OR ROUND TABLE INTERVIEW - managerial employees. APPLICATION FORM - Applicant is required to fill out the company’s official application form. IN-DEPTH INTERVIEW - Applicat formally enter into selection process. EVALUATING REFERENCE PHYSICAL EXAMINATION PLACEMENTS - after the applicant is cleared of all requirements is finally offered the job. ORIENTATION TRAINING KNOWLEDGE - better understanding to the psychology of a person EMPATHY - must be able to know the inner behavior of the individual by understanding his own personality and relate this feeling to the applicant. COMMUNICATION SKILLS - Refers to the use of language, gestures, and voice inflection. Words must be carefully chosen. PROBATIONARY - The probationary employee can be terminated if he does not pass the required reasonable standards in the job. REGULAR OR PERMANENT EMPLOYEE - an employee who passed the probationary period and performing regular activity in the business. CONTRACTUAL EMPLOYEE - the employee is hired for a fixed period or a project. CASUAL OR SEASONAL EMPLOYEE - hired for a particular work or service, seasonal in nature. APPRENTICESHIP - the development of the required skills for a particular type of work. PANEL JOB INTERVIEW - faces several interviewers who take turns asking questions BEHAVIORAL OR EXPERIENCE - based interview – done to clarify incidents in the applicant’s past such as former jobs or life experiences. STRUCTURAL INTERVIEW - pre-established questionnaire based on job descriptions. UNSTRUCURED INTERVIEW JOB OFFER - If he/she accepts the offer, the new hire will be accorded the position title, a summary of the job responsibilities. TRAINING - is the process where people acquire capabilities to aid in the achievement of organizational goals. - Started during the stone age when people started transferring knowledge through signs and deeds to others. - Vocational training started during the Industrial revolution (operation of machines). PRODUCTIVITY ENHANCEMENT - productive as soon as possible. TURNOVER REDUCTION - tends to stay longer. Organization effectiveness. BASIC SKILLS - skills needed to perform the job effectively. ADVANCED SKILLS - Use of Technology to share with other employees. ASSESSMENT PHASE ORGANIZATIONAL ANALYSIS - to help organization accomplish its objective. Grievances, accident record, observations, exit interview, customer’s complaints. TASK ANALYSIS - observing them how they perform their tasks. Changes in the work environment due to introduction of new technology. PERSON ANALYSIS - studying employee behavior. Whether Performance meets standards of the company. The use of performance appraisal in making individual analysis

Vocab - Cell Cycle, Interphase, Mitosis

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