Introducing 

Prezi AI.

Your new presentation assistant.

Refine, enhance, and tailor your content, source relevant images, and edit visuals quicker than ever before.

Loading…
Transcript

Chapter 8

Cell Structure and Function

Big Idea

Big Idea

Cellular Basis of Life, Homeostasis

Key Question: How are cell structures adapted to their functions?

Life is Cellular

Section 8.1

The Discovery of the Cell

Early Microscopes

In the late 1500’s, eyeglass makers in Europe found that they could use several glass lenses together to make very small things easy to see

In 1665, Robert Hooke used a microscope to look at thin slices of cork from plants - he discovered “boxes” and named them cells

Cells - the basic unit of all forms of life

Around the same time, Anton van Leeuwenhoek used a single lens microscope to observe pond water and discovered a whole world of tiny, living organisms.

The Cell Theory

The Cell Theory

Cell Theory

A fundamental concept of biology that states that:

i. All living things are composed of cells

ii. Cells are the basic units of structure/function in living things

iii. New cells are produced from existing cells

Exploring the Cell

Exploring the Cell

Light Microscopes and Cell Stains

A light microscope lets light pass through an object

Its two lenses focus the light to form an image

Only work up to 1000 times magnification

Electron Microscopes

Used to study very small things such as DNA

Focus beams of electrons using magnetic fields to create an image

Can show things that are 1 billionth of a meter is size

2 types: Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM)

Prokaryotes and Eukaryotes

Prokaryotes & Eukaryotes

Two main kinds of cells:

Eukaryotes

Organisms whose cells contain a nucleus

Prokaryotes

Unicellular organisms that lack a nucleus

Nucleus

A structure that contains the cell’s genetic material in the form of DNA

Prokaryotes

Prokaryotes

  • Generally smaller and simpler cells
  • Also known as bacteria
  • DNA floats freely in the cell and DOES NOT contain a nucleus
  • Still complete all of the activities that living things must do to be called alive (growth, reproduction, responsiveness, movement)

Eukaryotes

Eukaryotes

  • Generally larger and more complex
  • Most have dozens of structures and membranes inside them and many are highly specialized
  • A NUCLEUS is Present, separating the genetic material (DNA) from the rest of the cell
  • Can be very different from one another - can range from single-cell protists to trillions of different cells in humans
  • In multicellular organisms, cells are specialized for specific tasks. such as support, communication, movement, or the production of proteins or other cell products.
  • So cells in multicellular organisms cannot survive individually, they work together.

Cell Structure

Section 8.2

Cell Organization

Cytoplasm

The fluid portion of the cell outside the nucleus

Organelles

A specialized structure that performs important cellular functions within a eukaryotic cell; “little organs”

The Nucleus

The Nucleus

Control center of the cell

Holds nearly all of the cell’s DNA

Surrounded by a nuclear envelope dotted with holes (nuclear pores)

Organelles that Store, Clean Up, and Support

Organelles that Store, Clean Up, and Support

Vacuoles and Vesicles

Vacuole

The cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Found in both plant and animal cells

Vesicles

Membrane sacs that store and move materials between organelles as well as to and from the outside of the cell

Lysosomes

Lysosomes

Lysosome

The cell organelle that breaks down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell

Found in animal cells and some special kinds of plant cells

The Cytoskeleton

Cytoskeleton

Cytoskeleton

The network of protein filaments in a eukaryotic cell that gives the cell its shape and internal organization and is involved in movement

Contains two types of protein filaments:

Microfilaments - threadlike structures made up of a protein called actin

Microtubules - thin, hollow pipe made up of proteins known as tubulins

Organelles that Build Proteins

Organelles that Build Proteins

Ribosomes

Ribosome

A cell organelle consisting of RNA and protein found throughout the cytoplasm in a cell; the site of protein synthesis

Can be free floating in the cytoplasm or attached to the Rough ER

Endoplasmic Reticulum

Endoplasmic Reticulum

Endoplasmic Reticulum

The internal membrane system found in eukaryotic cells; the place where lipid components of the cell membrane are assembled

Rough ER - ribosomes on the surface make it “bumpy”

Smooth ER - no ribosomes on its surface

Golgi Apparatus

Golgi Apparatus

Golgi Apparatus

An organelle in cells that modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell

Organelles that Help Capture and Release Energy

Organelles that Capture and Release Energy

Chloroplasts

Chloroplast

An organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

Contain chlorophyll

Mitochondria

Mitochondria

Mitochondria

Cell organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use; the “power plant” of the cell

Cellular Boundaries

Cellular Boundaries

Cell Walls

Jobs are to support, shape, and protect the cell

Most prokaryotes and many eukaryotes, such as plant cells, have cell walls

Animal cells do NOT have cell walls

Cell Membranes

Cell Membranes

Lipid Bilayer

A flexible double-layered sheet that makes up the cell membrane and forms a barrier between the cell and its surroundings

Protects the cell, regulates what enters/exits, allows for flexibility

ALL cells have cell membranes

Cell Transport

Section 8.3

Passive Transport

Every cell needs to be able to control what crosses its membrane

Cells want to balance fluid outside of the cell with fluid inside the cell

Diffusion

Diffusion

Diffusion

The process by which particles tend to move from an area where they are more concentrated to an area where they are less concentrated

Particles will ALWAYS move from high to low

Does NOT require energy from the cell - this is why it is a type of passive transport

Facilitated Diffusion

FacilitatedDiffusion

Facilitated Diffusion

The process of diffusion in which molecules pass across the membrane through cell membrane channels

These act as short cuts for important molecules such as glucose

Does NOT require energy from the cell - passive transport

Osmosis

Osmosis

Osmosis

The diffusion of water through a selectively permeable membrane

Selectively permeable - some things can cross while others cannot

Many cells have water channel proteins (aquaporins) that allow water to pass right through

Osmotic Pressure

Osmotic Pressure

Osmotic Pressure

The pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

Three Types:

Isotonic

Hypertonic

Hypotonic

Isotonic Solutions

Isotonic

Isotonic

The concentration is the same inside and outside the cell; water moves at the same rate in both directions

Hypertonic Solutions

Hypertonic

Hypertonic

The outside solution has a higher concentration than the solution inside the cell; movement of water molecules outside the cell causes it to shrink

Hypotonic Solutions

Hypotonic

Hypotonic

The outside solution has a lower concentration than the solution inside the cell; water molecules move into the cell causing it to swell

Active Transport

Active Transport

The movement of particles across the cell membrane using energy

Three major kinds:

Protein Pumps - chemical energy is used to pump ions across the cell membrane

Endocytosis - membrane forms a pocket around a particle outside the cell and brings the item into the cell

Exocytosis - vesicle inside the cell carries a particle to the cell membrane and forces the particle outside the cell

Homeostasis and Cells

Section 8.4

The Cell as an Organism

All living things have certain characteristics in common

They are all made of cells

They all have the same kinds of organelles

Homeostasis

The relatively constant internal physical and chemical conditions that organisms maintain

Multicellular Life

Multicellular Life

The cells of human beings and other many-celled organisms do not live on their own - they need other cells to survive

These cells have to communicate with one another to maintain homeostasis

Cell Specialization

Different kinds of cells have different jobs

Each cell only completes its own jobs to keep the organism alive

Levels of Organization

Levels of Organization

Cells

Tissue

A group of similar cells that perform a particular function

Organ

A group of tissues that work together to perform closely related functions

Organ System

A group of organs that work together to perform a specific function

Organism

Cellular Communication

Cellular Communication

Cells in large organisms use chemical signals to communicate

These signals can speed up or slow down the activities of the cell

Passed across cellular junctions - the meeting point between cells

Learn more about creating dynamic, engaging presentations with Prezi