BTY 100 Lec3 2 Cell Organelles Outline Introduction

BTY 100 -Lec#3. 2 Cell Organelles

Outline Introduction to Cell Organelles Cell structure Cell Functions

Why do I need to study cell parts • Suppose you want to drive a car. • To drive a car you first need to know its parts and functions. Similarly we will be studying about cells is this course and therefore you need to know about its parts and their functions.

Cell Organelles Building blocks of Cell Provide Compartmentalization

Cell Wall • Tough, rigid layer that surrounds some types of cells. • Located outside the cell membrane. • Different composition in different cells Bacteria: Peptidoglycan Fungi: Chitin. Plants: Cellulose Animals: Missing

Functions • Provides structural support and protection. • Acts as a pressure vessel, preventing overexpansion when water enters the cell.

Plasma membrane • Every cell is surrounded by a plasma membrane, a continuous membrane composed of a lipid bilayer with proteins floating within it and protruding from it. • Fluid-Mosaic Model: Fluid: Lipids Mosaic: Proteins Introduce the term Biomolecules for lipids and proteins

• Roles of the plasma membrane: Acts as a selectively permeable barrier. Is an interface for cells where information is received from adjacent cells and extracellular signals. Allows cells to maintain a constant internal environment. Has molecules that are responsible for binding and adhering to adjacent cells.

Cytoplasm Consists of primarily of water, salts (ions), organic monomers and polymers, the building blocks of large macromolecules. It also contains various organelles as well as dissolved gasses and nutrients.

Membrane Bound Organelles • Double Membrane – Nucleus – Mitochondria – Chloroplast • Single Membrane – Endoplasmic Reticulum – Golgi Apparatus – Lysosomes • Non Membranous – – Ribosomes Cytoskeleton Centrioles Cillia and Flagella

Double Membrane Bound Organelles

Nucleus rts. a p e in th e term a l p x E e th alc u d o eri t Intr a m tic Gene nd genes a DNA Introduce the terms

• Known as the “ control centre of the Cell” – a membrane-bound sac evolved to store the cell’s chromosomes(DNA) – stores the genetic material of the cell in the form of multiple, linear chromosomes – To control the activity of cell by regulating gene expression – surrounded by a nuclear envelope composed of 2 phospholipid bilayers – in chromosomes – DNA is organized with proteins to form chromatin

Mitochondria and Chloroplast Organelles With DNA Mitochondria : Known as power house of the cell. Chloroplasts: Known as kitchen of the cell found in photosynthetic organisms

Mitochondria • Break down fuel molecules and convert the energy in the bonds of glucose and oxygen to readily available energy in the form of ATP. (cellular respiration) – Glucose – Fatty acids • exterior and interior membranes • Fluid is called matrix • interior partitioned by cristae

Chloroplasts Contain chlorophyll for photosynthesis Parts: Thylakoids are membranous sacs within the inner membrane and Grana are stacks of thylakoids. Fluid inside is called stroma 17

Single Membrane Organelles

Endoplasmic Reticulum Is a set of folded membranes and tubes throughout the system. The general structure: Membranous network of cisternae. Two types: Rough endoplasmic reticulum Smooth endoplasmic reticulum Introduce basic difference: Ribosomes

Functions • Provides a large surface area on which chemical reactions can take place. • It synthesizes lipids, phospholipids and steroid. • It also carries out the metabolism of carbohydrates, drug detoxification. • Attachment of receptors on cell membrane proteins. • RER involved in protein synthesis

Golgi Apparatus • Collection of Golgi bodies • Cisternae – stacked membrane folds • Front - Cis , Back – Trans • Collect, package, and distribute molecules synthesized at one location in the cell and utilized at another location • Vesicles from the endoplasmic reticulum fuse with the network and subsequently progress through the stack to the trans Golgi network, where they are packaged and sent to their destination

Lysosomes • Organelles that contain hydrolase enzymes that break down waste materials and cellular debris.

Disposal Bags/ Suicidal Bags of Cell • Cell damaged- membranes of Lysosomes breakenzymes release- components of cells brokenavailable for surrounding cells. • Also play part in normal development of an organism. • Lysosomes combine with food vacuoles. Eg: Paramecium • Used in destruction of engulfed harmful microbes

Vacuoles and Vesicles Vacuoles and vesicles are storage organelles in cells. Vacuoles are larger than vesicles. Either structure may store water, waste products, food, and other cellular materials. In plant cells, the vacuole may take up most of the cell's volume. The membrane surrounding the plant cell vacuole is called the tonoplast.

Non-Membranous Organelles

Ribosomes • Ribosomes are RNA-protein complexes composed of two subunits that join and attach to messenger RNA. • Site of protein synthesis • Each ribosome is divided into two subunits: the smaller subunit and the larger subunit

Cytoskeleton Network of protein fibers supporting cell shape and anchoring organelles q. Actin filaments: Cell movement q. Intermediate filaments: Stable- don’t break down q. Microtubules: Hollow tubes, Facilitate cell movement Functions: Supports the shape of the cell keeps organelles in fixed locations helps move materials within the cell

Cytoskeleton

Cilia and flagella § Both cilia and flagella are constructed from microtubules § Both provide locomotion for the cell

Plant or animal cell?

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