Eukaryotic Cell Structure

Organelles

Eukaryotic Cell Structure

Eukaryotic cells contain many structures that act as specialized organs known as organelles

Eukaryotic cells are classified into two major parts: 1) the nucleus, and 2) the cytoplasm – the portion of the cell outside of the nucleus

Nucleus

is the control center of the cell contains the genetic material known as

DNA (deoxyribonucleic acid) DNA provides the instructions for making

proteins and other important molecules contains chromatin - consists of DNA

bound to protein → condenses to form chromosomes

Ribosomes

Proteins are assembled (synthesized) on the ribosomes produce proteins by following coded

instructions that come from the nucleus

* Cells that synthesize a lot of proteins are filled with ribosomes

Analogy: a machine in a factory / construction workers

Endoplasmic Reticulum (ER)

internal membrane system of the cell site where lipid components of the cell

membrane are assembled, as well as proteins and other materials that are exported from the cell

Analogy: an assembly line

Endoplasmic Reticulum cont.

Rough ER – involved in the synthesis and modification of proteins → lined with ribosomes

Smooth ER – contain enzymes that synthesize membrane lipids

Golgi Apparatus

modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or secretion outside of the cell

Analogy: customization shop / postal service

Lysosomes

filled with enzymes → proteins involved in chemical reactions

digest, or breakdown, lipids, carbohydrates, proteins, and even organelles that have outlived their usefulness (they remove junk)

Analogy: recycling center

Vacuoles

saclike structures that store materials, such as: water, salts, proteins, and carbohydrates

Analogy: Storage Garage

Vacuoles cont.

in plants, there is often a large central vacuole filled with fluid the pressure of the central vacuole makes it

possible for plant cells to support heavy structures such as leaves and flowers

Vacuoles are also found in some unicellular and animal cells a contractile vacuole pumps excess water out

of the cell important for homeostasis

Mitochondria and Chloroplasts

All living things require a source of energy most cells get energy in one of two ways:

from food molecules or from the sun

* Both organelles contain their own genetic information

Mitochondria

convert chemical energy stored in food into compounds that are more convenient for the cells to use

enclosed by two membranes

Analogy: Coal-Burning Power Plant

Chloroplasts

contained in plant cells and some other organisms

capture energy from the sunlight and convert it into chemical energy through a process called photosynthesis

enclosed by two membranes

Analogy: Solar Powered Cells

Cytoskeleton

supporting structure and transportation system of the cell gives cells their shape and internal

organization microfilaments and microtubules

make up a cells cytoskeleton centrioles → important in cell division