Chapter 3 Anat of Cell Flashcards
Anatomy of the nucleus
Made up of nuclear membrane, nucleoplasm (gel-like substance similar to cytoplasm),chromatin and nucleolus
Cell Membrane
Flexible, elastic barrier between inner cytoplasm and outside world. It has a phospholipid bilayer with floating proteins. Two thin layers with dark space between them. Can be described as a fluid mosaic, Proteins have carb chains. Also has some cholesterol. Each individual cell is like a corporation (Example is “Hostest”) The cell membrane. - transportation and distribution. (Also called the plasmalemma).
Describe Centrioles
small hollow cylinders composed of 9 triplets of microtubules, pericentriolar material, asters. They are found in the center of the centrosome. They duplicate themselves in preparation for mitosis. They form the bases of microvilli, flagella and cilia
Chromatin
The substance of chromosomes. Dark or light fibers in the nucleoplasm which contains DNA and histones. Structure- single strand of DNA wraps around 8 histone molecules forming a granule called a nucleosome. These nucleosomes are held together by linker DNA. Chromatin stays invisible in the nucleus until mitosis.
Describe Cilia
Cilia occur in large numbers on the exposed surface of some cells. They are shorter than flagella and measure only about 10 m long. They move synchronously, one after the other, creating waves of motion that propel fluid, mucus, and debris across the cell surface. Cilia are best known for their important functions (1) in the upper respiratory tract, where they propel bacteria and mucus away from the lungs, and (2) in the oviduct, where their beating motion pulls the ovulated egg away from the ovary and into the opening of the oviduct. Cilia are more common than flagella in mammal cells.
Describe Flagella
Flagella generally occur singly and are significantly longer than cilia. They are typically attached to individual cells and propel the cell forward by undulating. Flagella move cells through fluid, whereas cilia move fluid across cell surfaces. The tail of a sperm cell is an example of a flagellum.
Describe the nuclear envelope. How is it different from the cell membrane
The nuclear envelope is composed of a lipid bilayer. The outer layer of the nuclear envelope is continuous with the endoplasmic reticulum, studded with ribosomes and nuclear pores complexes—places where the two layers of the nuclear envelope have fused to form a channel. It also has a perinuclear cisterna (space between the layers and an inner layer). Although the nuclear envelope is similar in structure and composition to the cell membrane, passage of molecules into the nucleus is less selective because the nuclear pore complexes are relatively large (0.1 nm in diameter).
Difference between prokaryotes and eukaryotes
Prokaryotes don’t have nuclei. Eukaryotes have a nucleus, in which DNA has formed chromosomes, and is surrounded by a nuclear envelope.Prokaryotes have no membrane-bound organelles. Eukaryotes are found in all multi-cellular organisms
Robert Hooke
In 1665, Robert Hooke was the first to observe cork cells and their characteristic hexagonal shape, using the first optical microscope, which was invented by him at that time.
Eukaryotic Cell
Distinct nucleus, DNA (combined with protein to form chromosomes), and membrane-bound organelles. Found in all multicellular organisms
Flagella/Cilia general characteristics
Energetic motile hairs that are extensions of the plasma membrane. They originate from pairs of basal bodies just under the plasma membrane. Extend out of the cell (into extra cellular space)
Peripheral Proteins
Peripheral proteins are bound either to the inside or outside surface of the cell membrane. They can act as enzymes to catalyze chemical reactions and may help change the cells shape
Golgi Apparatus
Stacks of cisternae (flattened sacs). Close to smooth ER. Acts as the sorter -modification, packaging and distribution center of molecules destined for secretion or intracellular use. Makes vesicles
How are centrioles structurally similar to cilia and flagella
Centrioles are structurally similar to cilia and flagella because all consist of microtubules. Centrioles are small, hollow cylinders composed of microtubules. Cilia and flagella are composed of nine pairs of microtubules that encircle a central pair of microtubules.
How do histones play a role in gene regulation
Histones help determine which segments of DNA will be expressed and therefore which proteins will be made. By wrapping around nucleosomes, histones help keep the DNA strand organized and untangled. They also expose small sections of the DNA (genes) to the outside nucleoplasm. By changing shape, the histones can expose different sections of DNA, at different times. Exposed genes determine what proteins will be made by the cell. In this way, histones play an important role in regulating gene expression (gene regulation).
Relationship of ribosomes and protein
Ribosomes manufacture protein. Protein intended for intracellular use is distributed through the ribosomes in the cytoplasm. Protein intended for extracellular use or use in the plasma membrane is synthesized on the rough ER
List organelles
nucleus, nucleolus, rough and smooth ER, golgi appartus, lysosomes, ribosomes, mitochondria, cilia, flagella, microvilli, peroxisomes and vaults (13)
Lysosomes
Specialized vesicles formed by the Golgi Apparatus. Contains digestive enzymes enclosed in a protective envelope. Breaks down nutrients and molecules and digests cellular debris. Lysosomes may also release their enzymes outside the cell to assist with the breakdown of extracellular material. (soldier)
Probably less important - In addition, lysosomal digestion is responsible for decreasing the size of body tissues (for example, shrinkage of the uterus after parturition and atrophy of muscles in paralyzed animals).
Mathew Scheiden and Theodor Schwann
Developed the theory that all things are made of cells in the 1830s
Membrane receptors
Are integral proteins and glycoproteins and act as binding sites on the cell surface
What can pass through the cell membrane
Most lipid soluble materials pass through the membrane, as do very tiny molecules (O2, CO2). Water Soluble molecules (AA, sugars, proteins) do not. They need to use “express ways or toll roads” which are the floating proteins
Microtubules
Long hollow tubes that grow out from nucleus. Microtubules have several functions. They provide the rigid, organized components of the cytoskeleton that give shape to many cells, and they are major components of centrioles, cilia and flagella. They also form secure “cables” to which mitochondria, lysosomes, and secretory granules attach.
Less important - Proteins that act as “motors” move the attached organelles along the microtubule from one location in the cell to another. Because microtubules act as the “railroad tracks” for organelle travel, they can be easily disassembled and then reassembled to form new paths or take a new direction.
Mitochondria
The powerhouse of the cell. Largest of the organelle. Produces most of the energy to fuel the cell. It’s structure: Outer membrane, inner membrane (made of cristae), matrix, DNA, RNA, enzymes. Remarkably, mitochondria contain their own DNA, which includes the instructions for making the enzymes used to make ATP.
Modern cells evolve from…
Pre-existing cells
Name 3 structures all mammalian cells posses
The animal cell structure is composed of the cell membrane, cytoplasm, and cell organelles.
Name the types of fiber that make up the cytoskeleton. How do they function differently?
Microtubules
Intermediate fibers
Microfilaments
nucleoli
One or more dark staining spherical patches in the nucleus. Not membrane bound and located where ribosomal subunits are made. Contains DNA to govern synthesis of rRNA (ribosomal RNA)
Peroxisomes
Membranous sacs containing enzymes. Formed by pinching off ER. Detoxifies and attacks free radicals (hydrogen peroxide). Destroys fat (Gym Trainer). Peroxisomes are commonly found in liver and kidney cells and are important in the detoxification of various molecules.
