Biology Unit 1: Microscope and Cell Structure

• Science - Unit 1 Biology Test contains multiple choice and short answer questions.

Microscope

• An instrument for visualizing fine detail of an object is a light microscope.
• Major parts of a compound microscope are the ocular lens, arm, body tube, coarse adjustment, nosepiece, stage, fine adjustment, objectives, stage clips, diaphragm, and base.

Cell Structure and Function

• A cell is the smallest unit of life.
• The cell theory includes:
  • All living things are made up of one or more cells and their products.
  • The cell is the simplest unit that can carry out all life processes.
  • All cells come from other cells; they do not come from non-living matter.
• Unicellular organisms are made up of one cell. Examples are Bacteria, Yeast, and Amoeba.
• Multicellular organisms are made up of many cells. Examples are humans, animals, and pie trees.
• Prokaryotic cells do not have a nucleus or other membrane-bound organelles. Example: Bacteria
• Eukaryotic cells have a nucleus and other organelles, each surrounded by a thin membrane.
• An organelle is a small structure inside a cell.

Organelles and Their Functions

• Cell wall: A protective layer that supports the cell; found only in plant cells.
• Cell membrane: Supports the cell and allows some substances to enter.
• Cytoplasm: A jelly-like fluid that holds all the organelles within a cell.
• Nucleus: Controls all activity in the cell and contains DNA; not found in prokaryotic cells.
• Endoplasmic Reticulum (ER): Transports materials such as proteins through the cell.
• Ribosomes: Build proteins in the cell; some float, some are attached to the ER.
• Golgi bodies: Package the proteins to be shipped out of the cell.
• Vacuoles: Store water, food, and waste. Plant cells have one large vacuole; animal cells have many small ones.
• Lysosomes: Break down food particles and destroy invaders like bacteria.
• Mitochondria: The "powerhouse" of the cell, makes energy and carries out functions.
• Chloroplasts: Contain chlorophyll (makes plants green); found only in plant cells.

The Importance of Cell Division

• Cell division includes reproduction, cell growth, and cell repair.
• Parent cell: The original cell.
• Daughter cell: A newly formed cell.
• Asexual reproduction: Involves one parent, which divides into two identical daughter cells.
• Sexual reproduction: A cell from one parent joins with a cell from another parent (meiosis).
• DNA: Contains genetic information with a backbone of sugar and phosphate, building blocks are C, G, A, and T (nitrogenous bases).
• A always matches with T (Adenine & Thymine).
• G always matches with C (Guanine & Cytosine).
• Gene: A segment of DNA that provides instructions to make proteins.
• Chromatin: A thread-like structure made up of DNA.
• Chromosome: A condensed thread-like structure made of DNA; humans have 46.
• Sister chromatids: Identical copies formed by the DNA of a chromosome.
• Diffusion: Movement of chemicals through a cell.
• Concentration: The amount of substance in a given volume of solution.
• Osmosis: Water enters and leaves cells by a process called osmosis.
• Every cell needs enough surface area to service its volume.
• As a cell gets larger, the ratio of surface area to volume decreases.
• If a single cell grows too large, diffusion and osmosis become ineffective.

Basic Needs of a Cell

• Energy: Cells need energy for functions like growth and reproduction.
• Nutrients: Cells require materials like proteins and carbs for survival.
• Communication: Cells need systems to regulate and respond to their environment.

Cell Cycle and Asexual Reproduction

• The cell cycle is the continuous sequence of cell growth and division.
• Interphase: The longest stage for most cells, but not a resting stage.
  • G1 Phase: Grows physically larger, makes proteins.
  • S Phase: DNA is duplicated.
  • G2 Phase: Begins to reorganize its contents in preparation for mitosis
• Spindle fibers: Help separate chromosomes during cell division.
• At each checkpoint, specialized proteins monitor cell activities and send messages to the nucleus.
  • A cell should remain in interphase and not divide if:
  • Signals from surrounding cells tell the cell not to divide.
  • There are not enough nutrients to provide for cell growth.
  • The DNA within the nucleus has not been replicated.
  • The DNA is damaged.

Cell Division Gone Wrong: Cancer

• Tumour: An abnormal growth of cells, forming clumps and reducing the effectiveness of other body tissues.
• Benign tumor: Non-cancerous.
• Malignant tumors: Cancerous, interfere with the functioning of surrounding cells.
• Metastasis: The process where cancer cells spread from the primary tumor to other body parts, forming secondary tumors, and making cancer more dangerous.
• Cancer cells lose control by bypassing cell cycle checkpoints, allowing them to divide uncontrollably without proper regulation.
• Mutations can occur from genetic errors or external factors; cancer risk can be reduced through healthy lifestyle choices, with treatments including surgery, chemotherapy, and targeted therapies.

Level of Organization and Cell Specialization

• Hierarchy cells: Levels of organization
• Tissue: A collection of similar cells that perform a particular, but limited, function.
• Organs: A structure composed of different tissues working together to perform a complex body function.
• Organ system:A system of one or more organs and structures that work together to perform a major vital body function such as digestion or reproduction.
• Organism: Any living thing.
• All cells start their lives as identical cells called Stem cells
• Stem cells can develop into different types of specialized cells based on which parts of its DNA are switched on. This process is called cell differentiation
• Totipotent (embryonic) stem cells:
  • These stem cells can become any kind of cell in the body Early in human development (embryos)
• Pluripotent (tissue) stem cells:
  • These stem cells can become are less versatile (capable of producing specific kinds of cells Late in development and after birth Only skin stem cells can produce cells to repair skin, and only bone stem cells can repair bone.
• Blood Stem cells The blood found in the umbilical cord immediately following birth is a rich source of stem cells
  • They can develop into any of the various kinds of blood cells.
  • This collected blood could be "banked" (stored) in case it is needed later in the child's life. Example: treatment for childhood cancers such as leukemia.
• Three main factors that influence differentiation in animal cells:
  • Contents of the cell's cytoplasm Contents of the cytoplasm may differ in each daughter cell.
  • For example, one daughter cell may have more storage vacuoles than the other.
  • Having more of these vacuoles will allow the cell to use more energy as it grows. Environmental conditions, such as temperature
  • Some conditions include temperature and the presence/absence of certain nutrients.
  • Differences in environmental conditions can also explain why cells with identical genes will develop differently

Influence of Neighbouring Cells

• Has one of the biggest influences on what a cell will become
• When cells are close to one another, the substances produced by one cell can sometimes diffuse through a neighbouring cell's membrane
• These substances can then change how the information in the DNA of the second cell gets expressed

Types of Animal Tissues

• Epithelial: Lines the surfaces of the body (body covering and between internal organs) Made of cells with strong connections between adjoining cell membranes, so they form a barrier
• Muscle: Designed to change their shape Act by shortening or lengthening
• Nervous: Made of cells called neurons, which have finger-like projections to receive and transfer signals Coordinates body actions
• Connective: Strengthens, supports, protects, binds, or connects cells and tissues Consists of cells that can range from a liquid (in blood), to elastic materials that can stretch (in ligaments), to mineral deposits (in bone)

Digestive System

• The digestive system is the organ system that takes in, breaks up, digests food and then excretes the waste

Parts of the Digestive System and Their Functions

• Mouth - Digestion begins in the mouth Mechanical breakdown - Teeth/tongue break down food into smaller pieces Chemical breakdown - An enzyme in saliva, called Amylase, starts the chemical breakdown
• Esophagus - After the food is broken up and swallowed, it passes through the Pharynx into the esophagus The muscular walls of the esophagus contract and relax, pushing each chunk of food along until it gets to the stomach known as peristalsis The Epiglottis is a "lid" or flap that covers the trachea during swallowing
• Stomach - The stomach is a J-shaped muscular organ that contracts to break down our food mechanical digestion The stomach releases gastric juices to continue the chemical breakdown of the food including: Hydrochloric acid Enzyme pepsin - Breaks down protein Pepsin needs an acidic environment to work The stomach lining also secretes mucus, which protects the stomach wall from breaking down in the presence of strong gastric juices Nerves in the stomach wall can Sense the presence of food and signal the stomach's muscle tissue to mix the contents. Also Signals when we have had enough to eat The gastric juices and the churning of the stomach muscles breaks down the food into a liquid
• Small intestine - When the meal is fully mixed, a round muscle at the bottom of the stomach-called A sphincter-relaxes and some of the contents of the stomach are released into The small intestine The first metre of the small intestine is called the duodenum, which is where most digestion takes place The duodenum has small tubes called ducts that connect to the pancreas, liver, and gallbladder They release more digestive enzymes which completes the chemical breakdown of the food. When the digested food moves into the remaining length of the small intestine, it is ready to be absorbed into the body The small intestine is covered with millions of interior folds, called villi and microvilli They maximize the surface area over which nutrients and water can be absorbed into the bloodstream
• Large intestine - The final organ is the large intestine, which includes the colon, rectum, and anus Main functions are: Absorb water, vitamins, and various salts from the digested food Eliminate undigested food through the anus as feces i.e, material in the cell walls of plants The large intestine also contains a community of healthy bacteria that Finish breaking down food Produce essential nutrients, such as vitamin K A by-product of bacterial metabolism is gas
• Accessory Organs - The liver also produces a fluid that helps in the breakdown of fats in our food- Called bile The pancreas produces an important enzyme called insulin which regulates the concentration of glucose (a sugar) in the blood The gall bladder also helps with the digestion of food by supplying digestive enzymes
• Goblet cells The entire length of the digestive tract is lined with epithelial tissue This tissue has goblet cells that secrete mucus The mucus serves two functions: Protects the digestive tube from digestive enzymes Allows the material to pass smoothly along the tube The digestive tube also includes layers of muscle tissues and nerves
• 4 Phases of Digestion Ingestion - intake of nutrients/food Digestion - breakdown of nutrients into smaller units by: Physical - mechanical breakdown of food Chemical - chemicals break down food Absorption - taking nutrients into cells Elimination - excretion of waste

Circulatory System

• Main functions of the circulatory system
• The three parts of the circulatory system and what they do Blood
• Blood is a type of connective tissue that circulates throughout the body Consists of four components Red blood cells Contains a protein called hemoglobin which allows them to transport oxygen throughout the body (most plentiful) White blood cells
• Infection-fighting cells that recognize and destroy invading bacteria and viruses (less than 1% of the volume of blood) Platelets Tiny cells that help in blood clotting (less than 1% of the blood) Plasma
• Protein-rich liquid that carries the blood cells along (over half of blood's volume) Heart
• The heart is a muscular organ that is made up of three different types of tissue Cardiac muscle tissue
• Only found in the heart. As they contract the pressure pushes the blood around the body Nerve tissue Connective tissue The heart is a powerful pump that beats an average of 60-100 times per minute The heart has 4 chambers
• Blood vessels Blood vessels are the tubes of the circulatory system and they carry blood There are 3 main types: Arteries
• Arteries carry blood AWAY From the heart (often oxygenated blood) The walls of arteries are thick because it is under great pressure Veins
• Veins carry blood towards the heart (deoxygenated blood) Has thin walls because it deals with lower blood pressure Capillaries
• Capillaries are extremely small, thin-walled blood vessels that connect arteries and veins They bring blood into close contact with the tissues in organs throughout the body Bring blood into contact with the small intestine's villi and microvilli to pick up nutrients from digested food and delivers it to cells in the body (nutrient exchange) Bring the blood into close contact with tissue in the lungs, where it picks up oxygen (gas exchange) Blood in the capillaries picks up wastes from cells and transports them to the kidneys and lungs, where they are removed from the bloodstream

Heart Anatomy

• Left atrium: Top left chamber of the heart, The left atrium of the heart receives oxygen-rich blood from the lungs
• Left ventricle: Bottom Left Chamber of the heart, Then, the oxygen-rich blood moves into the left ventricle, which pumps the blood out to the body cells through a huge artery called the aorta
• Right atrium: Top Right Chamber of the heart, The deoxygenated blood (filled with carbon dioxide) from our body travels through the right atrium
• Right ventricle: The bottom right chamber of the heart, to the right ventricle that pumps the blood to the lungs through the pulmonary artery to be exhaled
• Aorta: Carries oxygenated blood to the body
• Pulmonary artery: Carries deoxygenated blood to the lung The heart also has other smaller arteries
• 4 valves:Flexible flaps of tissue called valves are found throughout the circulatory system, including the heart and veins They open when blood is pushed through them, and then close to prevent blood from flowing backward
• When doing physical activity your pulse quickens due to the fact that you need blood to your muscles so they can flex and contract, so your heart needs to pump that blood faster
• Diseases Hypertension - high blood pressure Arteriosclerosis - thickening of the walls of the arteries, which narrows the passageway for blood Hypertension and arteriosclerosis can cause the formation of blood clots Heart Diseases, often blockages, can be diagnosed with the aid of a special X-ray called an angiogram, in which a fluorescent dye is injected into the bloodstream
• Heart attack - when an artery becomes completely blocked by clotting or plaque, preventing the blood from being pumped to the body. (diagnosed by blood tests and Electrocardiogram)
• Stroke - like a heart attack but is a blockage in the brain. When a stroke occurs, part of the brain is damaged due to oxygen deprivation A type of surgery called angioplasty uses a balloon or laser to try to open clogged arteries
• Anemia - a blood disorder that happens when you don't have enough red blood cells or your red blood cells don't work as they should Anemia is caused by a iron-deficiency

Respiratory System Anatomy

• Pharynx/Larynx: Your throat and holds vocal chords
• Trachea: Connecting the throat and lungs. The air moves into the trachea. Supported by rings of cartilage that keeps the trachea open and allows the air to flow freely A muscular flap, called the epiglottis, opens so air can pass When food is in the passage, the epiglottis closes so no food gets in the trachea
• Bronco: the airways that connect your windpipe to your lungs, branching into smaller tubes called bronchioles
• Bronchioles
• Alveoli:
• Diaphragm:Large sheet of muscle located beneath the lungs that helps us breathe in and out
• Ribs: Bones that protect our vital organs (ie. heart, lungs) and maintain space in the chest for breathing
• Gas exchange - Alveoli is where gas exchange occurs
• Diseases Asthma is a chronic respiratory disease that involves inflammation
• Pneumonia is an infection in the lungs by virus, bacteria or fungi
• Effects of Smoking - Can lead to lung cancer

Musculoskeletal and Nervous System

• Bones: store calcium and other minerals needed by organisms. Can store marrow which produces white and red blood cells
• Ligaments: tough, elastic connective tissues that hold bones together at the joins. Made if long fibers or collagen
• Cartilage: a dense connective tissue found in the ear, nose, esophagus, the disks between our vertebrae and joints. Provides a smooth surface preventing damage to the ends of bones
• Muscle tissue consists of bundles of long cells called muscle fibers that contain specialized proteins The proteins that cause our muscles to contract are signalled by nerve cells
• Tendons: Similar to ligaments but are less elastic and connect muscles to bones
• Nervous system: sensory input, Integration, Motor output Musculoskeletal system: support, Movement, protection
• Neurons are communication specialists Contains axons which are long thread like parts of neurons that carry signals Axons of some neurons are covered by fatty material called myelin (prevents electrical impulses)