Transcript Eukaryotic Cell Structure

Eukaryotic Cell
Structure
Chapter 7.2
The Eukaryotic Cell
• Divided into two major parts:
1. The nucleus
2. The cytoplasm
 Portion of the cell outside the nucleus
 Contains the organelles
Organelles
• Functional components of the cell
Each carries out a specific job
Determines the job of the cell
Work together to make the cell function
• Typically surrounded by a membrane
– Same membrane structure that surrounds
the cell
– Allows incorporation between organelles
and the cell membrane
How these notes work
• Red = Cell structure
• Green = Function
• Purple = Other information
• Picture = Structure (separate
slide)
The Nucleus
• The nucleus holds nearly all of the cell’s DNA
and with it the coded instructions for making
proteins and other important molecules
• control center of the cell
– Surrounded by a double membrane with pores in it
nuclear envelope outer boundary of the nucleus
• Houses genetic material and nucleolus
– Genetic material = DNA and proteins
– Nucleolus  makes ribosomes
The Nucleus
Genetic Material
• Chromatin
– Tangles mass of protein and DNA
• Chromosome
– Highly organized and compact mass of
protein and DNA
Chromatin becomes a chromosome
before cell division
Chromatin
Chromosome
Ribosomes
 Site of protein synthesis
 Composed of RNA and protein
 Can be attached or free-floating
Most common organelle
- found in prokaryotes as well
Endoplasmic Reticulum (ER)
• The site where lipid components of the cell
membrane are assembled; along with proteins and
other materials that re exported from the cell
• Two types
– Smooth ER – no ribosomes attached to it
Contains collections of enzymes that perform specialized
tasks (makes membrane lipids and detoxifies drugs)
– Rough ER – has ribosomes attached to it
Portion of ER where protein synthesis occurs
– Newly made proteins enter the ER and are modified
Golgi Apparatus
• The function of the Golgi Apparatus is to
modify, sort, and package proteins and
other materials from the ER for storage
in the cell or secretion outside the cell
Lysosomes
 Small organelles filled with digestive
enzymes
– Digestion of macromolecules into small
molecules that can be used by the rest of the cell
– Breakdown of organelles that have outlived their
usefulness
– Cell suicide organelles
Lysosomes
Vacuoles
 Store materials such as water, salts,
proteins, or carbohydrates
– One large vacuole is found in plant cells
• Allows the plant to grow tall
– Found in some single celled organisms
and in some animals
• Used to control the amount of water in the
organism
– Homeostatic mechanism
Mitochondria
 Convert the chemical energy stored in
food into compounds that are more
convenient for the cell to use
– Enclosed by two membranes
• Inner membrane is highly folded
– Called cristae
• FYI = All mitochondria come from your
mother
Chloroplast
 Capture the energy from sunlight and
convert it into chemical energy in a
process called photosynthesis
• Mostly found in plants (some other
single celled organisms)
– Surrounded by two membranes
• Highly stacked internal membrane
– Called the thylakoid
– Holds chlorophyll
Mitochondria and Chloroplast
• Both contain their own DNA
• Endosymbiotic theory
– Lynn Margolis suggested that ancient
mitochondria and chloroplasts were
independent prokaryotes
• Created a symbiotic relationship with early
eukaryotes
Cytoskeleton
 Network of protein filaments that help
the cell to maintain its shape
– Also involved in movement
• Principle protein filaments
– Microfilaments
– Microtubules
Centrioles / Cilia / Flagella
• Centrioles, cilia, and flagella are all made
of microtubules
• Centrioles
 Help to organize cell division
• Only in animal cells
• Cilia / Flagella
Hair-like projections that enable cells to
“swim” in a liquid environment