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Holt Cells, Heredity and Classification
Chapter 1: The Basic Units of Life
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Section 1: Diversity of Cells
Cell – the smallest unit that can perform all the processes necessary for life - cells are covered by a membrane and have DNA and cytoplasm
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Section 1: Diversity of Cells
Cells - the basic units of structure and function in living things. Form the parts of an organism Carry out all of organism’s processes, such as: obtaining oxygen, getting rid of waste, obtaining food, growing
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First Observations of Cells
Microscope - an instrument that makes small objects look larger. Made it possible to discover / learn about cells
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First Observations of Cells
Simple Microscope One lens Compound Microscope More than one lens
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Robert Hooke English scientist / inventor
One of the first people to observe cells used his microscope to observe a piece of cork Called the empty spaces cells - “little rooms” Thought animals weren’t made of cells since their cells didn’t have walls
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Anton van Leeuwenhoek Dutch businessman 1673 built his own microscopes
Observed fast-moving one-celled organisms in pond scum/water… called these animalcules Also observed blood, bacteria and yeast cells
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Anton van Leeuwenhoek Leeuwenhoek is a long, unusual word like animalcules
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Development of The Cell Theory
Almost 200 years passed before scientists concluded that cells are present in all living things 1838 – Matthias Schleiden concludes that all plants are made of cells
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Development of The Cell Theory
1839 – Theodor Schwann concluded that all animal tissues were made up of cells Schwann wrote first 2 parts of Cell Theory All organisms are made of one or more cells The cell is the basic unit of all living things.
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Development of The Cell Theory
1858 – Rudolf Virchow, a doctor, stated that all new cells could form only from other cells that already exist This then added the third part of the Cell Theory 3) All cells come from existing cells
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The Cell Theory The cell theory states that:
1) All organisms are made of one or more cells 2) The Cell is the basic unit of all living things. 3) All cells come from existing cells.
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Cell Size Most cells are too small to be seen without a microscope
No one knew cells existed until they could see them with a microscope Skin cells
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Cell Size As a cell’s volume increases, it’s surface area grows too.
surface area-to-volume ratio = volume
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Parts of a Cell Cell membrane = a protective layer that covers the cell’s surface and acts as a barrier between inside of a cell and the cell’s environment (outside)
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Parts of a Cell Cell membrane - controls what substances enter or leave the cell. 1 = cell wall 2 = cell membrane
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Parts of a Cell cell membrane - controls what substances enter or leave the cell. - all cells have them - acts like a window screen
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Parts of a Cell cytoplasm = fluid inside a cell
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Parts of a Cell organelles - structures that perform specific function within the cell. organs organelles - structures that - structures that carry out functions carry out functions in a body in a cell
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Different types of cells have different organelles
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Parts of a Cell Nucleus – in a eukaryotic cell; a membrane bound organelle that contains the cell’s DNA and has a role in processes such as growth, metabolism and reproduction the cell’s control center Acts as the brain of the cell
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Two Kinds of Cells prokaryote = an organism that consists of a single cell that does not have a nucleus Eubacteria and Archaebacteria
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Two Kinds of Cells eukaryote = an organism made up of cells that have a nucleus enclosed by a membrane animals, plants and fungi
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Section 2: Eukaryotic Cells
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Cell Wall cell wall - a rigid structure that surrounds the cell membrane and provides support to the cell Plants and algae have cell walls made of cellulose Fungi –yeast and mushrooms Onion cells
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Eukaryotic Cells cell wall - a rigid layer of nonliving material that surrounds the cells of plants and some other organisms. Helps to protect and support the cell Made mostly of cellulose (a strong material) Allows some materials (such as water and oxygen) to pass through
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Cell Membrane All cells have a cell membrane
Protective barrier that encloses a cell Separates contents from environment a gel-like fluid Contains proteins, lipids, and phospholipids
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Lipids – include fats and cholesterol, are a group of compounds that do not dissolve in water
Phospholipids – a lipid that contains phosphorous
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Cytoskeleton a web of proteins in the cytoplasm
acts as both a muscle and a skeleton keeps the cell’s membranes from collapsing helps some cells move made of 3 types of proteins
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Nucleus all eukaryotic cells have a nucleus a large organelle
contains the cell’s DNA = genetic material
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Nucleus Nucleus has a dark area of many cells called the nucleolus which is where a cell begins to make its ribosomes
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Ribosomes ribosomes – cell organelle composed of RNA and protein; the site of protein synthesis (small, grainlike bodies that produce proteins)
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Ribosomes ribosomes - small, grainlike bodies that produce proteins.
important chemicals needed to carry out bodily functions.
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Protein Jobs
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Endoplasmic Reticulum
endoplasmic reticulum – a system of folded membranes that in which proteins, lipids and other materials are made
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Endoplasmic Reticulum
The internal delivery system of the cell Its folded membranes contain many tubes and passageways Substances move through the ER to different places in the cell
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Rough ER Covered in ribosomes Usually found near nucleus
Ribosomes on rough ER make many of cell’s proteins ER delivers these throughout the cell
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Smooth ER Not covered in ribosomes
Functions include making lipids and breaking down toxic materials that could damage cell
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Mitochondria mitochondria – main source of power in a cell
- where sugar is broken down to produce energy
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Mitochondria energy released by mitochondria is stored in a substance called ATP which a cell used to do work
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Chloroplasts chloroplasts – where photosynthesis takes place
sunlight + CO2 + H2O =(makes) sugar + O2
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Chloroplasts only found in plant and algae
contain chlorophyll = makes plants green
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Golgi Complex Golgi complex - receives proteins and other newly formed materials from the endoplasmic reticulum, packages them, and distributes them to other parts of the cell, or outside the cell.
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Golgi Complex Lipids and proteins from ER may be modified to do different jobs Final products are enclosed in a piece of golgi complex’s membrane that is pinched off – forms a bubble and is transported to other parts of cell or out of cell
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Vesicle The bubble that forms from the golgi complex’s membrane is a vesicle A small sac that surrounds material to be moved in or out of cell
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Lysosomes lysosomes – vesicles responsible for digestion inside a cell
contain digestive enzymes destroy worn out or damaged organelles, get rid of waste materials and protect cell from foreign invaders mainly in animal cells
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Organelles in the Cytoplasm
vacuoles – large vesicle In plants & fungi may act like lysosomes Store digestive enzymes and aid in digestion within cell Other vacuoles in plant cell store water and other liquids to help support cell (or will wilt)
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Section 3 The Organization of Living Things
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Benefits of Being Multicellular
Larger size: even if small still larger than single celled organisms Longer life: life span not limited to that of a single cell Specialization: each type of cell has a particular job making the organism more efficient
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Cells Working Together
A tissue is a group of cells that work together to perform a specific job.
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Tissues Animals have 4 basic types of tissues: Nerve tissue
Muscle tissue Connective tissue Protective tissue
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TIssues Plants have three types of tissues: Transport tissues
Protective tissues Ground tissues – where photosynthesis takes place
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Tissues Working Together
A structure that is made up of two or more tissues working together to perform a specific function is called an organ Plants also have organs – example a leaf is a plant organ
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Organs working together
A group of organs working together to perform a particular function is called an organ system.
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Organisms Anything that perform life processes by itself is an organism. An organism can be single celled or multicellular.
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Organization of Cells cell tissue organ organ system
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Structure and Function
In organisms, structure and function are related. Structure is the arrangement of parts in an organism. Function is the job the part does.
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