HB p 25 Cells Since every living thing

HB p. 25 Cells

Since every living thing is made of cells, does that mean bigger organisms (like whales or elephants) have bigger cells? • • Not really! All organisms, no matter how tiny or how large are composed of cells. • There are different TYPES of cells (ex. Skin, bone, muscle, nerve), but all cells of a particular type are essentially the same size. • Therefore, the difference in cells in large vs. small organisms is the NUMBER of cells, not the SIZE!

How Were Cells Discovered? • New technologies lead to new discoveries • Robert Hooke - invented the first microscope and was the first to observe and name the small units that make up organisms. He called those small units cells because of the appearance of the structures in the dead cork he observed.

How Were Cells Discovered? • Anton van Leeuwenhoek improved the microscope and procedures for observing cells. He was able to clearly see living cells when observing the scrapings from his teeth.

Fill It In … Cells observed by … • Hooke: • Leeuwenhoek:

The Cell Theory Through the cooperative efforts of many individual scientists, a unifying cell theory developed: • All organisms are made of cells • Cells are the structural & functional units of organisms • Cells come from pre-existing cells

The Cell Theory

Prokaryotic vs Eukaryotic Cells • Are all cells alike? • Two main types of cells ….

Prokaryotic Cells • Simplest type of cell • Includes only bacteria. • Structure of a prokaryotic cell • No nucleus • No membrane-bound organelles • Includes: circular chromosome (DNA), plasmids (smaller rings of DNA, and ribosomes

Prokaryotic Cells- MYP • Thought to have a symbiotic relationship with Eukaryotic Cells • Nucleus • Mitochondria • Chloroplasts

Eukaryotic Cells • More complex than prokaryotic cells • Includes protist cells, fungi cells, plant cells, and animal cells (i. e. everything EXCEPT bacteria cells) • Structure of a eukaryotic cell • Chromosomes contained within a nucleus • In addition to ribosomes contains membrane-bound Cells : )

Fill It In … Prokaryotic Eukaryotic

Check Yourself! 1. Who first to observed dead cells? Who first to observed living cells? 2. What are the two main types of cells? 3. How is the location of the DNA different in prokaryotic and eukaryotic cells?

What do cells share? Structures found in ALL cells

DNA/Chromosome(s) • DNA organized as chromosome(s). DNA directs cell activity

Cytoplasm • Cytoplasm is the “filling” of the cell and is made of up to 90% water. Water provides the necessary environment for all the chemical reactions the cell needs

Ribosomes • Ribosomes are organelles that are the site of protein synthesis. Proteins are essential for enzymes, structure, and communication • Uses DNA code to synthesize proteins

Cell Membrane • Also called the Plasma Membrane

Fill It In … 4 structures found in ALL cells: 1. 2. 3. 4.

Cell Membrane • Composed of a phospholipid bilayer with embedded proteins. The fluid mosaic model describes the structure of the cell membrane

Cell Membrane • Fluid - individual phospholipids and proteins can move past each other; they are not fixed in one position • Mosaic - the membrane has more than one type of molecule (phospholipids & proteins)

Cell Membrane- MYP • Flexible/strong barrier • Some proteins from channel or pumps to allow things to go in and out of the cell • Carbohydrates are attached to membrane • These are used as chemical identification markers for the cell

Functions of the Cell Membrane • Selectively permeable - regulates what enters and leaves the cell. This helps maintain homeostasis • Gives the cell (cytoplasm) shape

Fill It In … The cell membrane is also called … And is S______ P_______

Structures (organelles) found in EUKARYOTIC cells

Fill It In … Organelle means …

1. Nucleus • Nucleus - surrounds the chromosomes for additional protection; is made of a phospholipid bilayer

Nucleus- MYP • Surrounded by nuclear envelope (lipid bilayer) • Nuclear pores • Chromatin- DNA bound to proteins • Chromosomes are condensed chromatin • Nucleolus- dense region where ribosomes are synthesized

2. Mitochondria • Mitochondria - site of cellular respiration which produces cell energy (ATP) • Active cells (muscle) -> hundreds of mitochondria • Inactive cells (fat) -> few mitochondria • Structure contains folded membranes which increases surface area allowing more space for more reactions • (MYP)-inherited through the ovum

3. Vacuole • Vacuoles - store food, waste or water to be used inside the cell or excreted from the cell. • Size differs in plant vs. animal cells • Much, much larger in plant cells … why?

4. Lysosomes • Lysosomes - contain digestive enzymes which digest food contained in vacuoles as well as old or damaged cell parts • (contain lipid bilayer)

5. Endoplasmic Reticulum (ER) • ER - a series of interconnected folded membranes that function in modifying (changing) proteins, detoxification of alcohols, and communication

ER (MYP) • Lipid components of the cell membrane are made here • Proteins and other material are exported or inserted into the cell membrane

Two Types of ER • Rough ER • Covered in ribosomes • Modify proteins

Two Types of ER • Smooth ER • Lacks ribosomes • Detoxification

6. Golgi Complex • Golgi Complex packages materials for export from cells • (MYP)- Modify, Sort, and Package • “finishing touches”

Plant Cell versus Animal Cell

Structures found ONLY in plant and plant-like cells • Chloroplasts organelles full of chlorophyll that are the site of photosynthesis which produces sugars (C 6 H 12 O 6) • Composed of folded membranes for more surface area

Structures found ONLY in plant and plant-like cells • Cell Wall provides extra support, protection, and shape for the cell • Found outside the cell membrane and made of cellulose

Structure found ONLY in animal cells • Centrioles organelle that helps with cell division in animal cells

Cytoskeleton (MYP) • Protein filaments to help maintain shape • May help with movement (amoeba) • Microtubules help with cell division (pulling the chromosomes)

Fill It In … Summary of structure/function: Nucleus Mitochondria Vacuole Lysosome ER Golgi Chloroplast -

Fill It In … Plant only Animal only

Check Yourself! 1. What four structures are found in all cells? 2. What is the function of the mitochondria? 3. What is the function of the ribosome? 4. What term refers to small cell structures? 5. What two structures are found in plant and plant-like cells?