Organelles of the Eukaryotic Cell

nucleus

nucleus

houses chromosomes (hold and protect the cell’s genetic information)

nuclear envelope

a cell membrane that encloses the nucleus; perforated by nuclear pores

nuclear pores

perforations in the nuclear envelope that allow proteins to pass in and mRNA to pass out

nucleolus

inside the nucleus; where ribosome assembly begins

cytoplasm

fluid portion of the cell that organelles float in; made of water, sugars, ions, and proteins; many cellular reactions occur in it

function of chromosomes

inside nucleus; made of tightly coiled DNA; store all of the organism’s genetic information (but only the needed genes in that specific cell type are switched on)

cell membranes

surround cells; made of a phospholipid bilayer; creates a selective barrier between the cell and its environment and embeds proteins in it

cell walls

only in plants, fungi, bacteria, and algae; provide structural support and protection for the cell

ribosomes

site of protein synthesis

How do vacuoles form?

by the fusion of multiple vesicles

difference of vacuoles between plants and animals

plants have a large central vacuole to store water; animals have many smaller vacuoles

vacuoles

store water, toxins, sugars, and ions

endoplasmic reticulum (ER)

produces proteins and lipids

rough ER

studded with ribosomes that produce transmembrane and organelle proteins

smooth ER

lacks ribosomes and is the site of lipid synthesis (fatty acids, phospholipids, steroid hormones)

Golgi apparatus

stacks of flattened membrane sacs (cisternae); further modifies proteins and lipids from the ER to make them usable for the cell, acts as a sorting station, site of glycosylation

glycosylation

the process in which sugars are covalently linked to lipids or proteins: takes place in the Golgi apparatus

lysosomes

generally only in animal cells; contain acidic enzymes that break down macromolecules and materials taken from outside the membrane through endocytosis

vesicles

transport substances from one organelle to another or to and from the cell membrane

How do vesicles form?

by pinching off, or “budding” from one membrane (ER) to the next (Golgi)

centriole

barrel shaped organelles from which microtubules grow; form spindle fibers (made of microtubules) that pull apart chromosomes during cell division

Which two energy processing organelles aren’t a part of the endomembrane system?

the mitochondria and chloroplasts

mitochondria

rod-shaped organelles with a double membrane (outer membrane and highly folded inner membrane); harness energy or organic molecules to produce ATP

mitochondrial matrix

the space enclosed by the inner membrane of the mitochondria

inter-membrane space

the area between the outer and inner membranes of the mitochondria

cellular respiration

a series of chemical reactions in which organic molecules are broken down and the energy stored in them is converted to ATP

How do the folds of the mitochondria relate to the process of cellular respiration?

the folds increase the surface area available for biochemical reactions that produce ATP, producing more ATP

chloroplasts

only in plant cells and green algae; have a double membrane and stacks of flattened sacs (thylakoids) grouped into stacks (grana); site of photosynthesis

photosynthesis

turning carbon dioxide, water, and light energy into oxygen and glucose

thylakoids

stacks of flattened sacs in the chloroplast; contain light-collecting molecules (pigments - chlorophyll)

function of the cytoskeleton

provides internal support for cells and helps determine cell shape

microtubules

hollow, structural rods that are assembled and disassembled when needed

microfilaments

extensively branch just beneath the cell membrane to reinforce the cell wall

function of microtubules and microfilaments

help with the process of cell division, help give the cell shape, help with cell movement

What are two cytoskeletal elements found in all eukaryotic cells?

microtubules and microfilaments