Year 8 Cells PDF

Cells Year 8, 2023 Your Learning Goals for this unit Be able to define what a cell is Become familiar with different cell types Gain an understanding of cell size Gain an understanding of the history of cells Be familiar with the function of a range of cellular organelles Know the di...

Cells Year 8, 2023 Your Learning Goals for this unit Be able to define what a cell is Become familiar with different cell types Gain an understanding of cell size Gain an understanding of the history of cells Be familiar with the function of a range of cellular organelles Know the difference between a plant and animal cell Be familiar with terms multicellular and unicellular Fun facts Every day 50 to 70 billion cells die in our body as way of keeping us healthy When cells are not functioning properly, our body suffers disease Cancer, can occur when cells keep dividing and do not stop (forming a tumor). Or when there is too much apoptosis (cell death) or too little. We all came from a single cell So what exactly are cells? Cells are the building blocks of life Cells make up living things Atoms make up matter Cells can only come from pre-existing cells Cells https://www.youtube.com/watch?v =Tfy1mOT-gEQ Cells can only be seen under a microscope Are larger than atoms Organisms are all living things Microorganisms – tiny living things Each cell – grows, reproduces and then dies Cell Theory All living things are made up of cells Cells are the basic building blocks of life Cells come from other cells The wacky history of cell theory (6 mins) What is a cell? There are two types of cells: - Plant cells - Animal Cells Both come in different shapes and sizes, however they all have three basic features… Plant cells also have extra features that make them different to animal cells Animal Cells Plant Cells To Do In your workbook, draw and label a diagram of a Plant, and Animal cell Make it colourful! Make sure it is clear an easy to read What are Organelles? These are all the parts inside the cell Each part has a special job, or function within the cell Different Organelles in an ANIMAL CELL Nucleus Cytoplasm Ribosomes Membrane Mitochondria Vacuole Lysosomes Golgi apparatus Endoplasmic reticulum The Nucleus The control centre of the cell Controls all of the activities within the cell Including the reproduction of other new cells Contains the DNA Cell Membrane The outer shell of the cell It encloses all of the organelles It is the skin that holds the cell together Controls what comes in and out of the cell Like the inside membrane of an egg shell Cytoplasm Jelly like mixture inside of the cell membrane All of the work of the cell happens in the cytoplasm The SPACE Like the egg white inside an egg shell Ribosomes Produce proteins – protein help with growth and repair Sometimes ribosomes are not enclosed in membranes so they are not always known as organelles Golgi Apparatus - A bunch of sacs (membranes) that prepare parts to leave the cell - Once they are all prepared they move through the cell membrane and leave the cell - Packages the protein Same as the golgi body Mitochondria Is the powerhouse of the cell It releases the energy from food to the cell Vacuole There may be many small vacuole in an animal cell Much smaller in an animal cell then a plant cell The vacuole contains waste or chemicals that move around the cell Lysosomes Gets rid of the waste within the cell Contains digestive enzymes to get rid of waste Endoplasmic Reticulum Forms pathways around the cell so materials can move around Rough "ER" is covered with ribosomes. It releases proteins and directs the proteins flow. Smooth "ER" has few or no ribosomes. It is a pathway for molecules to follow. Different Organelles in an PLANT CELL Cell membrane Nucleus Cytoplasm Cell wall Chloroplasts Vacuole Mitochondria Golgi Appartus Endoplasmic reticulum Lysosomes Different organelles in a Plant Cell Both animal and plant cell Unique to plant cells only organelles - Have a nucleus, cytoplasm, cell - Vacuole is much larger in a plant membrane, mitochondria, cell lysosomes, ER, etc - Have a cell wall as well as a cell - Have all the same, except plant membrane cells have a few more additions - They have chloroplasts Cell Wall It is outside of the cell membrane It helps support the plants shape Like the plants skeleton Chloroplasts They have chlorophyll and are in the green part of the plant Photosynthesis takes place in the chloroplasts Organisms with chloroplasts can make their own food Difference between Plant and Animal cells What is Photosynthesis? It is how plants get their food Their energy source They make their own energy from sunlight, carbon dioxide and water Photosynthesis Lesson 3 Recap organelles Worksheets: Match-up, cell organelles, and cell worksheet Unicellular and multicellular Introduction into mitosis Unicellular Cells Unicellular cells – Are prokaryotic cells They don’t have a true nucleus Often are bacteria cells Made up of a single cell Use mitosis for reproduction Multicellular cells Multicellular cells – Are Eukaryotic cells and have a nucleus Many cells Uses mitosis for growth and repair Help cells grow and repair Unicellular and Multicelluar organisms Mitosis Cell divides into two identical cells single -celled organisms (unicellular) use mitosis for reproduction Multicellular organisms use mitosis for growth and repair Mitosis is important for repair. Cells in multicellular organisms often wear out, or become damaged, and need to be replaced For example, each time you scrape skin of your knee after you fall, the damage is repaired by mitosis producing new cells Meiosis Creates the sex cells (also known as gametes, eg. sperm, eggs, pollen) Specialised Animal Cells Cells that have adapted unique structures and functions to perform specific tasks within the body. Examples include: - Nerve cells - Muscle cells - Blood cells - Fat cells  Attached to your Muscle Cells bones. Used for support and movement. - Voluntary muscles (Skeletal muscles) You choose to use them, so they are - Involuntary muscles (Smooth voluntary muscles. muscles) Eg. biceps and triceps - Cardiac muscles Striped in appearance like voluntary Muscles in your body that work muscles. Your HEART! without you having to think about it It never gets tired and beats all are called involuntary muscles. your life! Eg. diaphragm muscle that moves It has a very large number of mitochondria, supplying continuous up and down to bring air in and out energy. of lungs.  Nerve cells Nerve cells make up your brain. They also carry information from your brain to other parts of your body such as muscles, and from your muscles back to your brain. Some nerve cells have very long fibres extending from the cell called axons. Axons allow cells to carry Blood Cells (Red) Red Blood Cells - Specialized cells responsible for transporting oxygen from the lungs to the rest of the body - Carries carbon dioxide back to the lungs for exhalation - Contain a protein called hemoglobin - They are flat and have a biconcave (doughnut-like) shape, which increases their surface area for oxygen exchange and allows them to squeeze through narrow blood vessels Blood Cells (White) White Blood Cells - Are part of the immune system and play a crucial role in defending the body against infections and foreign invaders - There are several types of WBCs, including neutrophils, lymphocytes, and macrophages, each with specific functions such as engulfing pathogens, producing antibodies, and coordinating the immune response. Fat Cells Fat cells, or adipocytes, are specialized cells that store energy in the form of fat. They play a key role in regulating energy balance, insulation, and cushioning organs. There are two main types of fat cells in animals: white fat cells and brown fat cells. White Fat Cells - White fat cells store energy as large fat droplets, making up most of the body's fat tissue - Serve as an energy reserve, provide insulation to maintain body temperature - Cushion organs against physical impact - More common type of fat in the body. Brown Fat Cells - Contain smaller fat droplets and a higher number of mitochondria - Generates heat by burning calories, a process known as thermogenesis - Important in newborns and hibernating animals to maintain body temperature in cold environments. Specialised Plant Cells Specialized plant cells are adapted to perform specific functions that contribute to the overall health and growth of the plant. Each type of specialized cell has unique structures that enable it to carry out its role efficiently. Specialised Plant Cells Guard cells: Surround the stomata (pores) on the leaf surface and regulate gas exchange by controlling the opening and closing of the stomata. Conducting cells: Responsible for transporting water, nutrients, and food throughout the plant. Include xylem and phloem Root hairs: Increase the surface area of roots, enhancing the plant's ability to absorb water and minerals from the soil. Structural cells: Provide support and strength to the plant, helping it maintain its shape and withstand external forces. Photosynthetic cells: Mainly found in the leaves, contain chloroplasts and carry out photosynthesis, converting sunlight into energy for the plant. Cell to organism Chapter 2 Cells  Animal tissues and organs We learnt that Note: to be more complete, the diagram below should multicellular organisms have a fifth level with ‘organism’ at the top, for example: are made up of millions Cells → Tissues → Organs → Organ systems → Organisms of different types of specialised cells. Specialised cells are not just scattered randomly around the body. They are organised together with other cells of the same type, and often with other types of cells. There are several levels of organisation. See diagram. Cells, tissues, organs and organ systems Tissues Epithelial tissue Epithelial tissue is made up of cells that form surfaces (or outer layers) over other organs. Eg. your skin has an outer layer of epithelial tissue called the epidermis. Epithelial tissue lines your mouth, digestive system (eg. stomach lining), respiratory and reproductive systems. Connective tissue Connective tissue supports and holds together other tissues in the body. Eg. fat, bone, cartilage, ligament and tendon are connective tissues. Some types of connective tissue are strong and fibrous (made of fibres). Ligaments hold bones to other bones at the joints. A sprained ankle is actually a torn ligament (torn ligament fibres). Tendons join bones to muscles. Muscle tissue Muscle tissue is a specialised tissue that can contract, becoming shorter and fatter. Eg. your bicep muscle bulges when you pull up your forearm. Each individual cell of the muscle has contracted.  Nerve tissue Nerve tissue sends electrical signals around the body. These electrical signals are managed by the brain and passed down the large bundle of nerve tissue called the spinal cord to the body. One nerve cell can not pass information around your body effectively, so thousands of nerve cells group together to form your nerves. Organ s Tissues are grouped together into organs. All the different tissues contribute to the job that the organ has to do. There are many different organs in your body, such as the liver, kidneys and heart. Even your skin is any organ (the largest organ in your body). Organ systems An organ system is a series of organs that work together to complete a task. The digestive system is an organ system because it is a series of organs that work together to digest food.  questions Complete Question 1-6, 8 and 10 Page 85 Plant organs The root is the plant organ that takes water into the plant from the soil. Water moves through the cells to the vascular tissue. It moves up the xylem to the stem. The stem is an organ which holds the leaves up so they can capture light. Stems also carry water from roots to the leaves and glucose from the leaves to the rest of the plant. The leaves are the organ that carries out photosynthesis.  questions Complete Question 7, 9 and 15, Page 85