Biology: How life works (4th edition) Chapter 3 (4-5)

plasmodesmata

channels that allow the passage of large molecules like RNA and proteins between cells

cytoplasm

entire contents of cell other than nucleus

cytosol

jellyish internal environment of the cell that surrounds the organelles inside the cell membrane

How are organelles connected?

by vesicles or membrane bridges

vesicles

small-membrane enclosed sacs that transport substances

vesicles form by

forming off an organelle, taking a piece of the membrane and internal contents of organelle, fuse with another organelle or the membrane, unloading their contents

endomembrane system

made of interconnected membranes

what is included in the endomembrane system?

nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, cell membrane, and vesicles

Where do molecules within the endoplasmic reticulum go?

stay inside it, end up in interior of Golgi apparatus, or go outside the cell by fusing with a vesicle

exocytosis

when a vesicle fuses with the cell membrane, can empty its contents there or deliver proteins

endocytosis

vesicle buds off from cell membrane, enclosing material from outside and bringing it in

nuclear envelope

defines the boundary of the nucleus, consists of two membranes (lipid bilayers),

nuclear pores

openings in inner and outer membranes of nuclear envelope that connect them to each other, allow molecules to move into and out of nucleus

ribosomes

site of protein synthesis

protein synthesis

process in which amino acids are assembled into polypeptides guided by the information stored in mRNA

after exiting the nucleus mRNA....

binds to ribosomes

two types of ribosomes

free ribosomes in the cytosol, ribosomes associated with the endoplasmic reticulum

endoplasmic reticulum

outer of nuclear envelope is connected to this, involved in protein and lipid synthesis (produces and transports)

the ER consists of

a complex network of interconnected tubules and flattened sacs.

lumen

interior of endoplasmic reticulum

rough endoplasmic reticulum

synthesises transmembrane proteins, proteins that end up in the interior of organelles, and proteins destined for secretion, studded with ribosomes

cells that secrete large quantities of protein have

extensive rough ER

smooth endoplasmic reticulum

lacks ribosomes, site of fatty acid and phospholipid biosynthesis

cells specialized for the production of lipids will have

extensive smooth endoplasmic reticulum

golgi apparatus

modifies and sorts proteins and lipids as they move to their destination,next stop for vesicles that bud off ER

biosynthetic pathway

synthesis (ER), modification (GA), and transport of proteins (to rest of cell)

golgi apparatus roles

modifies proteins and lipids made by ER, sorts them, and adds carbohydrates to them

cisternae

stacks of flattened membrane sacs,

enzymes within the golgi apparatus

modifiers

glycoproteins

proteins attached to carbohydrates (sugars)

by moving from the GA to the ER

proteins are retrieved and membrane components can be recycled

lysosomes

specialized vesicles derived from golgi apparatus, degrade damaged or unneeded macromolecules

enzymes in lysosomes

break down macromolecules, packed in by GA

which membranes are not part of the endomembrane system?

mitochondria and chloroplasts (energy harnessers), they can still cross talk though

mitochondria

harness energy from chemical compounds and convert them into ATP, two membranes that fold into interior

ATP

universal energy currency of the cell

what is generated across the inner mitochondrial membrane?

a proton electrochemical gradient

Why is surface area important for mitochondria

more ATP is synthesized

chloroplasts

capture energy of sunlight to synthesize in simple sugars (photosynthesis), releases oxygen

thylakoid membrane

third, internal membrane of chloroplast, defines thylakoid, contains light-collecting pigments (chlorophyll)

Using light energy collected by chlorophyll, enzymes...

use carbon dioxide as a carbon source to produce carbohydrates

nucleus

storehouse for cell's genetic info and site for RNA synthesis

cytoskeleton

network of protein filaments and other associated proteins that provide the cell with an internal framework

peroxisomes

break down specific organic molecules such as fatty acids, and synthesize other organic molecules

cell wall

rigid barrier composed of polysaccharides

vacuoles

give plants structural rigidity by absorbing water and contributing to turgor pressure

matrix

cytosol of mitochondria, internal space

mitochondria structure

outer membrane, intermembrane space, inner membrane (cristae, is folded), matrix

structure of a chloroplast

three membranes, stroma (=cytosol of chloroplast), flattened vesicles

endosymbiotic theory

have same circular DNA and ribosomes as prokaryotic cells, were taken up into eukaryotic cell