Koo Bio 146 Chapter 6

Electron Microscope

Used to study subcellular structures

Scanning Electron Microscope

Focus a bean of electrons onto the surface of a specimen providing images that look 3D

Transmission Electron Microscope

Focus a beam of electrons through a specimen

Cell Fractionation

takes cells apart and separates the major organelles from one another. It enables scientists to determine the functions of organelles

Nucleoid

DNA in an unbound region

Cytoplasm

Bound by the plasma membrane

Eukaryotic cells

-DNA in the nucleus bounded by a membranous nuclear envelope

-Membrane bounded organelles

-Cytoplasm in the region between the plasma membrane and nucleus

Plasma Membrane

A selective barrier that allows sufficient passage or oxygen, nutrients, and waste to service the volume of every cell. General structure contains a double layer of phospholipids

nuclear lamina

Composed of proteins and maintains the shape of the nucleus

Chromosomes

In the nucleus DNA is organized into discrete units. These are composed of a single DNA molecule associated with proteins

Chromatin

The DNA and proteins of chromosomes together are called ___

Cell division

Chromatin condenses to form discrete chromosomes in preparation for ____ ______

Nucleolus

Located within the nucleus and is the site of ribosomal RNA synthesis

Ribosomes

Particles made of ribosomal RNA and protein. These carry out protein synthesis in the cytosol (free ribosome) and on the outside of the endoplasmic reticulum or the nuclear envelope (bound Ribosomes)

Endomembrane system

Nuclear Envelope

-Endoplasmic reticulum

-Golgi apparatus

-Lysosomes

-Vacuoles

-Plasma Membrane

Vesicles

Components of the endomembrane system are continuous or connected via transfer by _______

Endoplasmic Reticulum

Continuous within the nuclear envelope and accounts for more than half of the total membrane in many Eukaryotic cells

Smooth ER

No ribosomes

Rough ER

Surface studded with ribosomes

glycoproteins

(Functions of rough er)The rough ER has bound ribosomes, which secrete ____ (proteins covalently bonded to carbohydrates

Transport Vesicles

(Functions of Rough ER)Proteins surrounded by membranes

Golgi Apparatus

Shipping and receiving center, it consists of flattened membranous sacs called cisternae. Functions include: Modifying products of the ER, Manufacturing certain macromolecules, and it sorts and packages materials into transport vesicles

Lysosome

Membranous sac of hydrolytic enzymes that can digest macromolecules.

Lysosomal Enzymes

These enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids. They also work best in the acidic environment inside the lysosome

Phagocytosis

The process by which some types of cells can engulf another cell. This forms a food vacuole. A lysosome fuses with the food vacuole and digests the molecules. (Relates with autophagy)

Autophagy

Lysosomes also use enzymes to recycle the cell's own organelles and macromolecules

Vacuoles

Plant cells or fungal ells may have one or many of these. It's derived from the ER and Golgi apparatus

Food Vacuoles

formed by phagocytosis

Contractile vacuoles

Found in many freshwater protists, pump excess water out of cells.

Central Vacuoles

Found in many mature plant cells, hold organic compounds and water

Mitochondria

Sites of cellular respiration a metabolic process that uses oxygen to generate ATP

Chloroplasts

Found in plants and algae, are the sites of photosynthesis

Cristae

Located in the mitochondria it has a smooth outer membrane and an inner membrane folded into this _____

Mitochondrial Matrix

The inner membrane creates two compartments: inner membrane space and _____ ___

Thylakoids

Membranous sacs stacked to form granum (Part of the chloroplast structures)

Stroma

Internal fluid to the chloroplast structure

Plastids

The chloroplast is one of a group of plant organelles called _______

Peroxisomes

Specialized metabolic compartments bounded by a single membrane, produce hydrogen peroxide and convert it to water, perform reactions with many different functions. Still unknown how they relate to other organelles

Cytoskeleton

Network of fibers extending through the cytoplasm. It organizes the cell's structures and activities, anchoring many organelles. It's composed of three types of molecular structures: Microtubules, Miccrofilaments, and intermediate filaments

Motor proteins

Produces motility within the cytoskeleton

Microtubules

Thickest of the three components of the cytoskeleton. Hollow rods. It shapes the cell, guides movements of organelles, and separates chromosomes during cell division. Control the beating of cilia and flagella

Centrosomes

In many cells microtubules grow out from a ______ near the nucleus

Centrioles

In animal cells the centrosome has a pair of _______, each with 9 triplets of mirotubules arranged in a ring

Basal body

anchors the cilium or flagella

Dynein

it's a motor protein which drives the bending movements of a cilium or flagellum

Microfilaments

Also called actin filaments, are the thinnest components of the cytoskeleton

Intermediate Filaments

Fibers with diameters in a middle range. (Third part of components of the cytoskeleton)

Cortex

Microfilaments form a 3D network called the ____ just inside the plasma membrane to help support the cell's shape

Myosin

Microfilaments function in cellular motility contain this protein in addition to actin

Pseudopodia

(Cellular extension) extend and contract through the reversible assembly and contraction of actin subunits into microfilaments

Cytoplasmic streaming

Circular flow of cytoplasm within cells

Cell wall

Extracellular structure that distinguishes plant cells from animal cells

Primary cell well

relatively thin and flexible

Middle lamella

thin layer between primary walls of adjacent cells

Secondary cell wall

In some cells it is added between the plasma membrane and the primary cell wall

Extracellular Matrix

Animal cells lack cell walls but are covered by this____ _____

Collagen proteoglycans fibronectin

Extracellular matrix is made up of glycoproteins such as these 3

Integrins

Extracellular matrix proteins bind to receptor proteins in the plasma membrane called _____

Plasmodesmata

Channels the perforate plant cell walls

Tight junctions

Membranes of neighboring cells are pressed together preventing leakage of extracellular fluid

Desmosomes

Anchoring junctions...Fasten cells together into strong sheets

Gap junctions

Provide cytoplasmic channels between adjacent cells