Transcript Ribosomes
Bell-Ringer 1) What are organelles? a) parts of cells which help it divide b) substances which perform specific tasks for the cell c) parts of all cells which help the cell move through different environments d) substances which provide the cell with the energy needed to run life processes 2) The cell to the right is a... a) bacteria cell b) prokaryote c) monokaryote d) eukaryote 3) We know the answer to #2 because... a) The cell has a membrane-bound nucleus b) The cell has clearly defined organelles c) The cell has ribosomes in the cytoplasm d) The cell has a plasma membrane 4) The best reason to explain why cells are so small is... a) being small allows them to maximize their chemical reactions b) being small makes it easier to move materials in and out of the cell c) being small makes it harder for a cell to loose the organelles inside it d) being small gives the cell the ability to thrive in a variety of environments. Organelles -part 1- Cell Membrane • The cell membrane (and the membranes covering some organelles) are made of phospholipids. Cell Membrane • Phospholipids have two distinct parts: – A hydrophilic (water-loving) head – A hydrophobic (water-fearing) tail Cell Membrane • The lipids line up so that their polar heads point outward toward water and their tails point inward, away from water. Cell Membrane • Embedded within the plasma membrane are various types of proteins. Cell Membrane • These proteins perform specific tasks, such as: – Helping transport substances across the membrane – Signaling other cells Cell Membrane • Scientists describe a cell’s plasma membrane as being a “fluid mosaic.” • This means that the cell membrane acts more like a fluid than a solid. Cell Membrane • Members of the membrane can move around each other – the pattern of lipids and proteins in the membrane is constantly changing. • Example: The cell membrane is a lot like a layer of oil in a beaker of water. Nucleus • Most of the functions of eukaryotic cells are controlled by the nucleus. • The nucleus houses and protects the cell’s genetic information – its DNA. Nucleus • The nucleus houses and protects the cell’s genetic information – its DNA. • The nucleus is often found near the center of the cell. Nucleus • When a cell is not dividing, the DNA in the nucleus is found in the form of chromatin (stringy, thread-like DNA). • When a cell is dividing, the chromatin condenses to form chromosomes. Nucleus • The nucleus is covered by a double membrane called the nuclear envelope. • There are tiny holes in the envelope, nuclear pores, which allow materials to pass in and out of the nucleus. Mitochondria • The mitochondria is the power-house of the cell. Mitochondria • It is responsible for transferring energy from organic molecules to ATP. • ATP is the energy source that power’s all of the cell’s chemical reactions. Mitochondria • Because the mitochondria supply energy, highly active cells (like muscle cells) have a high number of mitochondria. Ribosomes Ribosomes • Ribosomes are small, spherical objects that are responsible for building proteins. • Ribosomes build proteins by attaching amino acids together. Ribosomes • Ribosomes are one of a few organelles that are not surrounded by a membrane. • Ribosomes are found in two places: – Floating freely in the cytoplasm – Attached to the Endoplasmic Reticulum Endoplasmic Reticulum There are two different types of Endoplasmic Reticulum: 1) Rough ER 2) Smooth ER Endoplasmic Reticulum • The Endoplasmic Reticulum (ER) functions as a cellular pathway. • It helps transport molecules from one part of the cell to another. Endoplasmic Reticulum • The Rough ER is covered in ribosomes. • It is responsible for transporting materials, as well as producing phospholipids and proteins. Endoplasmic Reticulum • Some ribosomes on the rough ER make digestive enzymes to help break down food. Endoplasmic Reticulum • The Smooth ER does not contain ribosomes. • Besides transporting materials, it is also responsible for creating numerous products: – Cholesterol – Estrogen / Testosterone Exit Slip 1) If you were to remove all the ribosomes from a cell, the cell would also not have... a) DNA b) Nucleic Acids c) Proteins d) Lipids 2) What biological compound is closely related to the mitochondria? a) Proteins b) ATP c) DNA d) Carbohydrates 3) Which answer below is the Endoplasmic Reticulum most like... a) a power plant – providing energy b) a brain – the control center c) a factory – making products d) a highway – transporting materials 4) What words best describe the plasma membrane? a) stiff conglomerate b) fluid mosaic c) liquid smooth d) strong mixture