Cell Structures - Organelles Biochemistry chapter 2 Cell Structures - Organelles

What do you know about cells?

WHY? Why learn about Biochemistry: Medicine – causes and cures for diseases. Nutrition – health and effect of nutritional deficiencies. Agriculture – improving crop cultivation and pest control. Watch https://www.youtube.com/watch?v=tpBAmzQ_pUE

Cell structures - organelles Are internal structures of cell that interact and complement each other. They carry out specialized functions. Examples? Analogy example? Shapes are elaborate – because each performs a specific function.

Types of cells Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not.

Types of cells Focus today: Plant & Animal Eukaryotic cells Have different requirements to get energy and food. Heterotrophic and autotrophic.

What is the difference between Animal & Plant cells? 1) What is the difference between Animal & Plant cells?

Outline - Organelles 1) Membranes. 2) Nucleus: Nucleolus. Nuclear membrane/envelope. 3) Endoplasmic reticulum 4) Vesicles, vacuole, and lysosomes. 5) Golgi Body. 6) Mitochondria 7) Chloroplast 8) Microtubules & Microfilaments, Cilia and flagella. 9) Cell Surface (Cell Wall). 10) Extracellular matric (ECM). https://www.youtube.com/watch?v=OtJnRokyLvc

Organelle – rarely works alone Just like organ systems work together to keep body functioning A team of organelles keep a cell running

3) Cell needs to reproduce itself to generate more cells. Why important to learn? 1) Substances move between different organelles and the plasma membrane. 2) Some metabolic pathways take place in a series of different organelles. 3) Cell needs to reproduce itself to generate more cells. Page 72 – check out the labeled plant & animal cell diagrams. Page 73 – check out the summarized table on eukaryotic cell organelles.

1) Membranes Cell and many organelles within are bounded by membranes that control amount and type of substances moving in and out. Plasma membrane (around the cell): form a barrier around the cytosol (which is a jelly-like substance in cells that hold the organelles). Membrane surrounding an organelle keeps an internal environment that allows the organelle to carry out its function. We’re GATEKEEPERS!

2) Nucleus In almost all eukaryotic cells. Contains almost all of the cell’s DNA small amount of DNA present in mitochondria and chloroplast. Protects the DNA (genetic material) in cell. Isolated in its own room - DNA stays separated from the activity of cytosol. Two components: Nuclear membrane. Nucleolus. I’m the CONTROL FREAK!

a) Nuclear envelope Double membrane surrounding the nucleus. Outer bilayer – continuous with Endoplasmic reticulum (ER) membrane. Has different kinds of membrane proteins embedded. Some are receptors and transporters. Others collect in tiny pores that span the membrane. Membrane proteins, with the lipid bilayer, work together to transport various molecules across the nuclear membrane.

Function? Allows water and gases to cross freely. Other substances can only enter and exit the nucleus with the help of a system of transporters and pumps. Ex: Cells access DNA when they make RNA and proteins. Allows only certain molecules to cross it at certain times and in certain amounts. WHY? Think of Charlie & The chocolate factory fence! The control is a measure of safety for DNA & for the cell to control production of RNA and proteins.

b) nucleolus Nucleus contains at least one nucleolus – a dense irregularly shaped region It is where ribosome subunits are assembled from proteins and RNA. p. 74 ( Figure 3)

2) What is the Nucleus and what are the 2 other components involved?

Outline - Organelles 1) Membranes. 2) Nucleus: Nucleolus. Nuclear membrane/envelope. 3) Endoplasmic reticulum 4) Vesicles, vacuole, and lysosomes. 5) Golgi Body. 6) Mitochondria 7) Chloroplast 8) Microtubules & Microfilaments, Cilia and flagella. 9) Cell Surface (Cell Wall). 10) Extracellular matric (ECM).

3) Endomembrane system ‘Factory’

Other function: destroying toxins and recycling waste. Group of interacting organelles between the nucleus and plasma membrane. Think of entering the factory from the first fence/gate all the way to seeing the management office that controls everything. Main Function: make lipids, enzymes, and proteins for secretion and insertion into cell membranes. Other function: destroying toxins and recycling waste. Think of factory departments. Components vary among different cell types, but most common are: a) Endoplasmic reticulum. b) Vesicles (including vacuole(s) and lysosomes). c) Golgi bodies.

a) Endoplasmic reticulum (ER): Extension of nuclear envelope. Continuous compartment that folds repeatedly into sacs and tubes. Two kinds: Rough ER (have ribosomes attached) Smooth ER

No ribosomes, so doesn’t make proteins. Smooth ER: No ribosomes, so doesn’t make proteins. Some polypeptides made in rER end up in smooth ER (ex: enzymes). These enzymes produce most of the cell’s membrane lipids. Also break down carbs, fatty acids, and drugs. Rough ER: Has ribosomes that synthesize polypeptide chains, which are then released into the interior of the ER. Inside, proteins fold into complex structure. Some proteins become part of ER membrane. Some carried to different places in cell. Note: cells that make or secrete lots of proteins, has lots of rough ER (ex: pancreatic gland cells make enzymes to digest food). I’m the HIGHWAY!

Different Shipping trucks b) Vesicles Membrane-enclosed saclike organelles. Form in great numbers – either on their own or by budding from other organelles or from plasma membrane. Many different types of vesicles – with many different functions: Some transport proteins between organelles, or from or to plasma membrane. Another type contains enzymes that digest fatty acid and amino acids (Ex: peroxisomes). Different Shipping trucks

Special two types of vesicles Animal cell 1) Vacuole Liquid-filled organelle that stores waste and helps in cell metabolism. In plants - large central vacuole. Amino-acids, sugars, ions, wastes and toxins are accumulated. Fluid pressure keeps plant cell firm (why leaves and stems are also firm). In animal cells – small and more. Plant cell Storage place

Special two types of vesicles 2) Lysosome Vesicles with powerful digestive enzymes. They fuse with vacuoles that carry particles for disposal (ex: worn-out cell components)l. Liposomal enzymes empty into vacuoles and digest their contents. Garbage Disposal

I’m the post office (specific stamps) 3) Golgi Bodies Many vesicles fuse with and empty their contents into Golgi body. It has a folded membrane – looks like stack of pancakes. Enzymes in it put the finishing touches on polypeptide chains and lipids delivered from ER. Ex: attach phosphate groups or sugars, and cleave polypeptide chains. End products (ex: proteins, proteins for secretion, enzymes) are sorted and packaged into new vesicles. Carried to the plasma membrane or lysosomes. I’m the post office (specific stamps)

Endomembrane Watch https://www.youtube.com/watch?v=Fcxc8Gv7NiU

3) Give a brief analogy describing the endomembrane system with all its 5 components!

Outline - Organelles 1) Membranes. 2) Nucleus: Nucleolus. Nuclear membrane/envelope. 3) Endoplasmic reticulum 4) Vesicles, vacuole, and lysosomes. 5) Golgi Body. 6) Mitochondria 7) Chloroplast 8) Microtubules & Microfilaments, Cilia and flagella. 9) Cell Surface (Cell Wall). 10) Extracellular matric (ECM).

Other organelles: 1) Mitochondria Specialized in making ATP. Nearly all eukaryotic cells have mitochondria. But prokaryotes do not. Most ATP is produced in a series of reactions that occur inside the mitochondria and require oxygen. With every breath, you take in oxygen which is then used by mitochondria. Number varies depending on cell type and organism. Ex: single cell yeast vs. human muscle cell. Cells with high energy demand – have more mitochondria.

Between 1 and 4 micrometers in length. Extra info: Between 1 and 4 micrometers in length. Has two membranes, one highly folded inside the other. Resemble bacteria in size, shape and biochemistry. They have their own DNA, divide independently of the cell, and have their own ribosomes. Endosymbiosis – mitochondria evolved from aerobic bacteria that permanently resided in a cell. https://www.youtube.com/watch?v=tdGjorwuEDw

2) Plastids Membrane-enclosed organelles – used for photosynthesis or storage only in PLANT cells. Common types: chloroplasts, chromoplasts, and amyloplasts. Chloroplasts: oval shaped organelles specialized for photosynthesis. Two outer membranes enclose stroma (a semifluid interior containing enzymes and chloroplast’s DNA). May have evolved via endosymbiosis too. Chloroplast: double-membrane bound organelle that contains enzymes and pigments that are used to perform photosynthesis in eukaryotic cells. https://www.youtube.com/watch?v=y8_G9olr2fA (till minute 1:00)

Outline - Organelles 1) Membranes. 2) Nucleus: Nucleolus. Nuclear membrane/envelope. 3) Endoplasmic reticulum 4) Vesicles, vacuole, and lysosomes. 5) Golgi Body. 6) Mitochondria 7) Chloroplast 8) Microtubules & Microfilaments, Cilia and flagella. 9) Cell Surface (Cell Wall). 10) Extracellular matric (ECM). https://www.youtube.com/watch?v=OtJnRokyLvc

Compare and contrast: Mitochondria and Chloroplast? 4) Compare and contrast: Mitochondria and Chloroplast?

Dynamic cytoskeletion Between nucleus and plasma membrane. Interconnected system of many protein filaments that: Provides cell structure. Helps with cell division. Enables the cell and inner organelles to move around. Ex: Microtubules and Microfilaments. Cilia, Flagella, and Pseudopods.

1) Microtubules and microfilaments Long hollow cylinder that consists of subunits of the protein tubulin. Rapidly assemble when needed, and disassemble when not needed. Ex: assemble before cell divides to separate chromosomes, then disassemble.

1) Microtubules and microfilaments Fibre that consists mainly of subunits of the protein actin. They strengthen or change the cell’s shape. Actin microfilaments which form at the edge of a cell, drag or extend it in a specific direction. Ex: in muscle cells, microfilaments of myosin and actin interact for contraction.

2) Cilia, Flagella, and Pseudopods. Flagella: whip-like structures that propel cells through fluid Ex: sperm movement through fluid. Cilia: tiny hairlike structures that move water and mucus in eukaryotes. Also used for movement of prokaryotes. Ex: coordinated movement of cilia on thousands of cells lining airways sweeps particles away from lungs. Pseudopods (false feet): lobes formed by amoebas and other eukaryotes. As these lobes bulge outwards, they move the cell and engulf a target as prey. Microfilaments force the lobes to advance in a steady direction.

5) List 3 examples of cytoskeleton components 5) List 3 examples of cytoskeleton components. Explain how at least one works.

Outline - Organelles 1) Membranes. 2) Nucleus: Nucleolus. Nuclear membrane/envelope. 3) Endoplasmic reticulum 4) Vesicles, vacuole, and lysosomes. 5) Golgi Body. 6) Mitochondria 7) Chloroplast 8) Microtubules & Microfilaments, Cilia and flagella. 9) Cell Surface (Cell Wall). 10) Extracellular matric (ECM).

The cell surface Many types of cells have a cell wall around the plasma membrane. Animal cells do NOT have a cell wall, but plant cells do. Cell wall: porous structures that protects, supports and gives cell shape. Water and many solutes easily cross it on the way to and from plasma membrane. Some plant cells are covered in outer waxy cuticle that helps protect exposed surfaces and limits water los on hot days.

Extracellular Matrix Most multicellular organism cells are surrounded by extracellular matrix (ECM). Non-living complex mix of fibrous proteins and polysaccharides that is secreted by cells. Functions: Supports and anchors cells., Separates tissues. Functions in cell signaling. Cell junctions - cell interacts with other cells and surroundings via them. Cells send and receive ions and signals through some junctions.

6) What is the difference between cell wall and cell membrane 6) What is the difference between cell wall and cell membrane? What is the structure and function of ECM?

Outline - Organelles 1) Membranes. 2) Nucleus: Nucleolus. Nuclear membrane/envelope. 3) Endoplasmic reticulum 4) Vesicles, vacuole, and lysosomes. 5) Golgi Body. 6) Mitochondria 7) Chloroplast 8) Microtubules & Microfilaments, Cilia and flagella. 9) Cell Surface (Cell Wall). 10) Extracellular matric (ECM). Organelle rap: https://www.youtube.com/watch?v=OtJnRokyLvc

Questions? https://www.youtube.com/watch?v=TYxDoP9ABHc Homework: Read chapter 2 section 1. Case study ‘ Little Girl Lost – A case Study on defective cellular organelles’: Read part 1 and 3. Answer questions on page 4 and 5. Remember resume and one-page report deadline.