Parts Of A Eukaryotic Cell

Front 1

Nucleus

Back 1

The ___ is the most obvious organelle in any eukaryotic cell. It is enclosed in a double membrane and communicates with the surrounding cytosol via numerous nuclear pores. Within each ___ is nuclear chromatin that contains the organism’s genome. The chromatin is efficiently packaged within the small nuclear space. Genes within the chromatin are made of deoxyribonucleic acid (DNA). The DNA stores the organism’s entire encoded genetic information. The DNA is similar in every cell of the body, but depending on the specific cell type, some genes may be turned on or off - that's why a liver cell is different from a muscle cell, and a muscle cell is different from a fat cell. When a cell is dividing, the nuclear chromatin (DNA and surrounding protein) condenses into chromosomes that are easily seen by microscopy.

Front 2

Nucleolus

Back 2

The prominent structure in the nucleus is the ___. The ___ produces ribosomes, which move out of the nucleus and take positions on the rough endoplasmic reticulum where they are critical in protein synthesis.

Front 3

Cytosol

Back 3

The ___ is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. Though mostly water, the ___ is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors.

Front 4

Cytoplasm

Back 4

This is a collective term for the cytosol plus the organelles suspended within the cytosol.

Front 5

Centrosome or MICROTUBULE ORGANIZING CENTER (MTOC)

Back 5

The ___, or _______, is an area in the cell where microtubules are produced. Plant and animal cell ____s play similar roles in cell division, and both include collections of microtubules, but the plant cell ___ is simpler and does not have centrioles.

During animal cell division, the centrioles replicate and the ___ divides. The result is two ___s, each with its own pair of centrioles. The two ___s move to opposite ends of the nucleus, and from each ___, microtubules grow into a "spindle" which is responsible for separating replicated chromosomes into the two daughter cells.

Front 6

Centriole (animal cells only)

Back 6

Each ___ is a ring of nine groups of fused microtubules. There are three microtubules in each group. Microtubules (and ___s) are part of the cytoskeleton. In the complete animal cell ___, the two ___s are arranged such that one is perpendicular to the other.

Front 7

Golgi Apparatus

Back 7

The ___ is a membrane-bound structure with a single membrane. It is actually a stack of membrane-bound vesicles that are important in packaging macromolecules for transport elsewhere in the cell. The stack of larger vesicles is surrounded by numerous smaller vesicles containing those packaged macromolecules. The enzymatic or hormonal contents of lysosomes, peroxisomes and secretory vesicles are packaged in membrane-bound vesicles at the periphery of the ___.

Front 8

Lysosome

Back 8

___ contain hydrolytic enzymes necessary for intracellular digestion. They are common in animal cells, but rare in plant cells. Hydrolytic enzymes of plant cells are more often found in the vacuole.

Front 9

Peroxisome

Back 9

___ are membrane-bound packets of oxidative enzymes. In plant cells, ___ play a variety of roles including converting fatty acids to sugar and assisting chloroplasts in photorespiration. In animal cells, ___s protect the cell from its own production of toxic hydrogen peroxide. As an example, white blood cells produce hydrogen peroxide to kill bacteria. The oxidative enzymes in ___s break down the hydrogen peroxide into water and oxygen.

Front 10

Secretory Vesicle

Back 10

Cell secretions - e.g. hormones, neurotransmitters - are packaged in ___ at the Golgi apparatus. The ___ are then transported to the cell surface for release.

Front 11

Cell Membrane

Back 11

Every cell is enclosed in a ___, a double layer of phospholipids (lipid bilayer). The exposed heads of the bilayer are "hydrophilic", meaning that they are compatible with water both within the cytosol and outside of the cell. However, the hidden tails of the phosopholipids are "hydrophobic" , so the ___ acts as a protective barrier to the uncontrolled flow of water. The ___ is made more complex by the presence of numerous proteins that are crucial to cell activity. These proteins include receptors for odors, tastes and hormones, as well as pores responsible for the controlled entry and exit of ions like sodium (Na+) potassium (K+), calcium (Ca++) and chloride (Cl-).

Front 12

Mitochondria

Back 12

___ provide the energy a cell needs to move, divide, produce secretory products, contract - in short, they are the power centers of the cell. They are about the size of bacteria but may have different shapes depending on the cell type. ___ are membrane-bound organelles, and like the nucleus have a double membrane. The outer membrane is fairly smooth. But the inner membrane is highly convoluted, forming folds (cristae) when viewed in cross-section. The cristae greatly increase the inner membrane's surface area. It is on these cristae that sugar is combined with oxygen to produce ATP - the primary energy source for the cell.

Front 13

Vacuole

Back 13

A ___ is a membrane-bound sac that plays roles in intracellular digestion and the release of cellular waste products. In animal cells, ___ are generally small. ___ tend to be large in plant cells and play several roles: storing nutrients and waste products, helping increase cell size during growth, and even acting much like lysosomes of animal cells. The plant cell ___ also regulates turgor pressure in the cell. Water collects in cell ___, pressing outward against the cell wall and producing rigidity in the plant. Without sufficient water, turgor pressure drops and the plant wilts.

Front 14

Cell Wall (plant cells only)

Back 14

Plant cells have a rigid, protective ___ made up of polysaccharides. In higher plant cells, that polysaccharide is usually cellulose. The ___ provides and maintains the shape of these cells and serves as a protective barrier. Fluid collects in the plant cell vacuole and pushes out against the ___. This turgor pressure is responsible for the crispness of fresh vegetables.

Front 15

Chloroplast (plant cells only)

Back 15

___ are specialized organelles found in all higher plant cells. These organelles contain the plant cell's chlorophyll responsible for the plant's green color and the ability to absorb energy from sunlight. This energy is used to convert water plus atmospheric carbon dioxide into metabolizable sugars by the biochemical process of photosynthesis. ___ have a double outer membrane. Within the stroma are other membrane structures - the thylakoids. Thylakoids appear in stacks called "grana".

Front 16

Smooth Endoplasmic Reticulum

Back 16

Throughout the eukaryotic cell, especially those responsible for the production of hormones and other secretory products, is a vast network of membrane-bound vesicles and tubules called the ____. The __ is a continuation of the outer nuclear membrane and its varied functions suggest the complexity of the eukaryotic cell.The _____ is so named because it appears smooth by electron microscopy. ___ plays different functions depending on the specific cell type including lipid and steroid hormone synthesis, breakdown of lipid-soluble toxins in liver cells, and control of calcium release in muscle cell contraction.

Front 17

Rough Endoplasmic Reticulum

Back 17

___ appears "pebbled" by electron microscopy due to the presence of numerous ribosomes on its surface. Proteins synthesized on these ribosomes collect in the ___ for transport throughout the cell.

Front 18

Ribosomes

Back 18

___ are packets of RNA and protein that play a crucial role in both prokaryotic and eukaryotic cells. They are the site of protein synthesis. Each ___ comprises two parts, a large subunit and a small subunit. Messenger RNA from the cell nucleus is moved systematically along the ___ where transfer RNA adds individual amino acid molecules to the lengthening protein chain.

Front 19

Cytoskeleton

Back 19

As its name implies, the ___ helps to maintain cell shape. But the primary importance of the ____ is in cell motility. The internal movement of cell organelles, as well as cell locomotion and muscle fiber contraction could not take place without the ___. The ___ is an organized network of three primary protein filaments:

*microtubules

*actin filaments (microfilaments)

*intermediate fibers