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STANDARD 2 Organization & Development of Living Systems Unit 2 – Cell Structure & Function Objectives • • • • • • B2.4h: Describe the structures of viruses and bacteria. B2.5g: Compare and contrast plant and animal cells. B2.5i: Relate cell parts/organelles to their function. B1.1E. Give evidence to support conclusions B1.2E Be aware of careers in science B1.2h Distinguish between theories, hypotheses and observations • B1.2i Explain progressions of ideas What is Biology? • • • • Bio- = life -ology = study of Biology= study of life 3 types of items • Living • Non living • Dead Carbon: The Element of Life (4:00) Characteristics of Life 6 Generally accepted characteristics common to all living things: 1. Cells – have at least one cell 1. Have coded “information molecules” with instructions for organization and activities. 2. Metabolism- Obtain and use energy from environment and give off byproducts 1. Heterotrophs = get energy from other organisms. 2. Autotrophs = synthesize their energy through photosynthesis / make their own food Characteristics of Life … • 3. Growth and Development • 4. Homeostasis – Ability to regulate internal environment - balance • 5. Reproduce - Make more of its kind; pass on genetic material • 6. Require Water • If something is not alive it is either non- living or dead. – What is the difference? Characteristics of Life (5:58) VIRUSES Where Do Viruses Fit? • Viruses are not classified as cells and therefore are neither unicellular nor multicellular organisms. • Most people do not even classify viruses as "living" because they lack a metabolic system and are dependent on the host cells that they infect to reproduce. • Viruses have genomes that consist of either DNA or RNA, and there are examples of viruses that are either double-stranded or single-stranded. Importantly, their genomes code not only for the proteins needed to package its genetic material but for those proteins needed by the virus to reproduce during its infective cycle. How Viruses Work (02:25) The Littlest Assassins: What Are Viruses? (03:35) Viruses Are viruses alive? - Viruses lack cellular structure but have genetic material to invade living cells. Bacteria Cell Structure Animal Cell Structure CELLS INTRODUCTION TO CELLS: • Discovered by Robert Hooke, an English naturalist. – He was looking at cork. – The cork was dead, but the cell walls remained. – Hooke coined the term "cells": the boxlike cells of cork reminded him of the cells of a monastery. – The term cell came from the Latin word cella which means "storeroom" or "small container". INTORDUCTION TO CELLS: • Anton Van Leeuwenhoek, a Dutch businessman and a contemporary of Hooke, used his own (single lens) monocular microscopes & discovered living cells 10 years later in pond water. – Leeuwenhoek succeeded in making some of the most important discoveries in the history of biology. It was he who discovered bacteria, free-living and parasitic microscopic protists, sperm cells, blood cells, microscopic nematodes and rotifers, and much more. BACTERIA Organisms Found in Pond Water: Bacteria and Algae (03:37) PROTISTS SPERM CELLS CELL THEORY The modern tenets of the Cell Theory include: * 1. All known living things are made up of cells. * 2. The cell is structural & functional unit of all living things. * 3. All cells come from pre-existing cells by division. (Spontaneous Generation does not occur). 4. Cells contains hereditary information which is passed from cell to cell during cell division. 5. All cells are basically the same in chemical composition. 6. All energy flow (metabolism & biochemistry) of life occurs within cells. The Living Cell (20:00) The concept was formally articulated in 1839 by Schleiden & Schwann. The cell theory also provides us with an operational definition of "life“. WHAT IS A CELL? • Cells are the structural and functional units of all living organisms. Some organisms, such as bacteria, are unicellular, consisting of a single cell. Other organisms, such as humans, are multicellular, or have many cells—an estimated 100,000,000,000,000 cells! Each cell is an amazing world unto itself: it can take in nutrients, convert these nutrients into energy, carry out specialized functions, and reproduce as necessary. Even more amazing is that each cell stores its own set of instructions for carrying out each of these activities. Cells – The Basic Units of Life (1:49) 2 TYPES OF CELLS: • 1. Prokaryote • • • • Single celled (unicellular organisms) Lack membrane bound organelles Single stranded DNA – no nucleus Most of the functions of organelles, such as mitochondria, chloroplasts, and the Golgi apparatus, are taken over by the prokaryotic plasma membrane. Example- only Bacteria • 2. Eukaryote • • • • • • More complex Have membrane bound organelles / nucleus Multiple strands of DNA in the nucleus include fungi, animals, plants as well as some unicellular organisms Eukaryotic cells are about 10 times the size of a prokaryote Example - Plants and animals 2 TYPES OF CELLS: Two Types of Cells: Prokaryotic and Eukaryotic (00:40) This figure illustrates a typical human cell (eukaryote) and a typical bacterium (prokaryote). The drawing on the left highlights the internal structures of eukaryotic cells, including the nucleus (light blue), the nucleolus (intermediate blue), mitochondria (orange), and ribosomes (dark blue). The drawing on the right demonstrates how bacterial DNA is housed in a structure called the nucleoid (very light blue), as well as other structures normally found in a prokaryotic cell, including the cell membrane (black), the cell wall (intermediate blue), the capsule (orange), ribosomes (dark blue), and a flagellum (also black). PROKARYOTES • Cells that lack a membrane-bound nucleus are called prokaryotes (from the Greek meaning before nuclei). • Cells in the monera kingdom such as bacteria and cyanobacteria (also known as blue-green algae) are prokaryotes. • Prokaryotic cells differ significantly from eukaryotic cells. They don't have a membrane-bound nucleus and instead of having chromosomal DNA, their genetic information is in a circular loop called a plasmid. Prokaryotic Cells (02:28) PROKARYOTES… • Bacterial cells are very small, roughly the size of an animal mitochondrion. • Prokaryotic cells feature three major shapes: rod shaped, spherical, and spiral. • Instead of going through elaborate replication processes like eukaryotes, bacterial cells divide by binary fission. • Bacteria perform many important functions on earth. They serve as decomposers, agents of fermentation, and play an important role in our own digestive system. • Also, bacteria are involved in many nutrient cycles such as the nitrogen cycle, which restores nitrate into the soil for plants. EUKARYOTES • Eukaryotic cells (from the Greek meaning truly nuclear) comprise all of the life kingdoms except monera. They can be easily distinguished through a membrane-bound nucleus. • Eukaryotic cells also contain many internal membrane-bound structures called organelles. These organelles such as the mitochondrion or chloroplast serve to perform metabolic functions and energy conversion. • The cell is the basic structural unit of life, and the smallest unit of biological entities that are considered "alive." EUKARYOTES… • Each cell represents a miniature organism, in a sense, in that cells perform necessary functions such as respiration, consumption of nutrients, and expulsion of metabolic wastes to continue their existences. • As such, cells have developed specialized structures called organelles to aid them in these specific functions such as respiration and photosynthesis. • Eukaryotic cells are much larger and more advanced than prokaryotic cells. • Most importantly, eukaryotes reproduce sexually. • Genetic material is mixed between two parents, and while the offspring resembles the parents in major features, minor genetic variations can yield subtle differences. The new characteristics sometimes help eukaryotic organisms to adapt to new environments. Eukaryotic Cells (03:22) Plant Cell Animal Cell EUKARYOTE ORGANELLES • ORGANELLES of eukaryotic cells (each has their own function): • The human body contains many different organs, such as the heart, lung, and kidney, with each organ performing 0a different function. Cells also have a set of "little organs", called organelles, that are adapted and/or specialized for carrying out one or more vital functions. Organelles are found only in eukaryotes and are always surrounded by a protective membrane. Plasma Membrane Cell Walls and Cell Membranes (01:53) A lipid/protein/carbohydrate complex, providing a barrier and containing transport and signaling systems. (controls movement in/out of cell to maintain homeostasis) Eukaryotic Cells: Nucleus (00:42) Nucleus Double membrane surrounding the chromosomes and the nucleolus. Pores allow specific communication with the cytoplasm. The nucleolus is a site for synthesis of RNA making up the ribosome. (brain of cell) EUKARYOTE ORGANELLES • Cytoplasm = Inside the cell there is a large fluid-filled space, it is the "soup" within which all of the cell's organelles reside. The nucleus often flows with the cytoplasm changing its shape as it moves. The cytoplasm also contains many salts and is an excellent conductor of electricity, creating the perfect environment for the mechanics of the cell. The function of the cytoplasm, and the organelles which reside in it, are critical for a cell's survival. (fills all empty space & allows movement & reactions) • Nuclear Envelope = The nucleus is spheroid in shape and separated from the cytoplasm by a membrane called the nuclear envelope. The nuclear envelope isolates and protects a cell's DNA from various molecules that could accidentally damage its structure or interfere with its processing. (protects nucleus / controls in/out)) EUKARYOTE ORGANELLES Mitochondria Organelles: Mitochondria (00:38) Surrounded by a double membrane with a series of folds called cristae. Functions in energy production through metabolism. Contains its own DNA, and is believed to have originated as a captured bacterium. Mitochondria play a critical role in generating energy in the eukaryotic cell, and this process involves a number of complex pathways. Once inside the cell, glucose is broken down to make adenosine triphosphate (ATP), a form of energy. (powerhouse of cell) Chloroplasts and Photosynthesis (00:50) Chloroplasts (plastids) Are similar to mitochondria but are found only in plants. Surrounded by a double membrane, containing stacked thylacoid membranes. Chloroplasts convert light energy from the sun into ATP through a process called photosynthesis. Contains DNA, and like mitochondria is believed to have originated as a captured bacterium. (collect sunlight for photosynthesis) EUKARYOTE ORGANELLES Rough endoplasmic reticulum (RER) A network of interconnected membranes forming channels within the cell. Covered with ribosomes (causing the "rough" appearance) which are in the process of synthesizing proteins for secretion or localization in membranes. (transport network) Ribosomes Making Proteins (01:54) Protein and RNA complex responsible for protein synthesis. The process of converting an mRNA's genetic code into the exact sequence of amino acids that make up a protein is called translation. Protein synthesis is extremely important to all cells, and therefore a large number of ribosomes—sometimes hundreds or even thousands—can be found throughout a cell. Ribosomes float freely in the cytoplasm or sometimes bind to another organelle called the endoplasmic reticulum. (protein factories) Smooth endoplasmic reticulum (SER) Endoplasmic Reticulum (00:43) A network of interconnected membranes forming channels within the cell. A site for synthesis and metabolism of lipids. Also contains enzymes for detoxifying chemicals including drugs and pesticides. (transport network) EUKAYOTE ORGANELLES Golgi apparatus A series of stacked membranes. Vesicles (small membrane surrounded bags) carry materials from the RER to the Golgi apparatus. Vesicles move between the stacks while the proteins are "processed" to a mature form. Vesicles then carry newly formed membrane and secreted proteins to their final destinations including secretion or membrane localization. (packages and distribution) Lysosomes (00:39) Often referred to as the garbage disposal system of a cell. One function of a lysosome is to digest foreign bacteria that invade a cell. Other functions include helping to recycle receptor proteins and other membrane components and degrading worn out organelles such as mitochondria. Lysosomes can even help repair damage to the plasma membrane by serving as a membrane patch, sealing the wound. It is a membrane bound organelle. (recycling centers) Lysosymes EUKARYOTE ORGANELLES Vacuoles Membrane surrounded "bags" that contain water and storage materials in plants. (store water and food in plants) Hyperlinked to interactive cell website Peroxisomes Often referred to as the garbage disposal system of a cell. Peroxisomes function to rid the body of toxic substances, such as hydrogen peroxide, or other metabolites and contain enzymes concerned with oxygen utilization. High numbers of peroxisomes can be found in the liver, where toxic byproducts are known to accumulate. (remove toxics from cell) Cell wall Plants have a rigid cell wall in addition to their cell membranes. (protects and gives shape) 2 TYPES OF EUKARYOTIC CELLS: • 1. ANIMAL • 2. PLANT – organelles unique to plant cells: • Cell Wall – protects and gives shape • Chloroplasts – collect sunlight for photosynthesis • Vacuole – large water filled storage compartment ANIMAL CELL PLANT CELL Lab 1 Fresh Mount Examples: Animal Cells (Human Cheek cells) Stained 4x objective Animal Cells (Human Cheek cells) Stained 40x objective Animal Cells (Human Cheek cells) Stained 10x objective Lab 1 Fresh Mount Examples: Plant Cells (Onion Epidermal Cells) 4x objective Plant Cells (Onion Epidermal Cells) 40x objective Plant Cells (Onion Epidermal Cells) 10x objective Lab 1 Fresh Mount Examples: Plant Cells (Elodea) 10x objective Plant Cells (Elodea) 40x objective Working Together • Major systems and processes work together in animals and plants, including relationships between organelles, cells, tissues, organs, organ systems, and organisms. • During the development of an animal, cells differentiate so they can perform specific functions. Groups of cells with similar specializations that form a common function are referred to as a tissue. Organs are groups of several tissues that function together. Examples of organs include kidneys, spleen, liver, heart, lungs. Organ systems is a group of organs that work together to perform a function. Examples of organ systems include skeletal, muscular, nervous, digestive, respiratory, reproductive, endocrine, circulatory, and urinary systems. Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism Working Together • Hierarchical Structure of Life / Pyramid Of Life • When you look at a pyramid, you'll notice that its broad base gradually narrows as it extends upward. The same holds true for the organization of life on Earth. • Atom – Our tour starts with the ever so tiny atom. It takes extremely powerful microscopes to view these units of matter (anything that has mass and takes up space). Elements such as carbon, oxygen, and hydrogen are composed of atoms. • Molecules – Molecules reign supreme on the next level. Molecules are composed of atoms and can be arranged into large molecular structures such as chromosomes, proteins, and membranes. Some of these proteins may be grouped together to become the organelles that make up your cells. • Organelle – Cells also have a set of "little organs", called organelles, that are adapted and/or specialized for carrying out one or more vital functions. Organelles are found only in eukaryotes and are always surrounded by a protective membrane. Working Together • Cells – The next level-- cells. Cells are the simplest form of living units. Cells contain structures called organelles which are responsible for everything from housing the cell's DNA, to producing energy. Processes that occur within the body are carried out on a cellular level. For example, when you move your leg, it is the responsibility of nerve cells to transmit these signals from your brain to the muscle cells in your leg. • Tissues – Next, we have tissues. No, not the kind you use to blow your nose! Simply put, tissues are groups of cells with both a shared structure and function. Animal tissue can be grouped into four subunits: epithelial tissue, connective tissue, muscle tissue, and nervous tissue. Working Together • Organs – Next, we arrive at the organs: i.e., the heart, liver, brain, skin, and stomach. Organs are composed of different types of tissue arranged together to perform specific tasks. For example, the brain is composed of several different types including nervous and connective tissues. • Organ Systems – Moving right along, we come to our next level--organ systems. Some examples are the circulatory, digestive, nervous, skeletal, and reproductive systems which work together to keep the body functioning normally. For instance, nutrients obtained by the digestive system are distributed throughout the body by the circulatory system. Likewise, the circulatory system distributes oxygen that is taken in by the respiratory system. • Organism – When all organ systems function together to form any living being, or organism, whether plant, mammal, bird, insect, reptile, fish, crustacean, aquatic or estuarine animal, or bacterium. These living beings have (or can develop) the ability to act or function independently. Basics of Biology, The: The Human Body: Organ Systems Working Together (14:39)