MCAT Bio Cell C1 CN

The domains of life

Archaea, Bacteria, Eukarya

Cell Theory

1. All living things are composed of cells.

2. The cell is the basic functional unit of life.

3. Cells arises only from preexisting cells.

4. Cells carry DNA passed from parent to daughter cell.

Cell Theory Viruses

Contain genetic material but unable to reproduce on their own. Violates third and fourth tenets of cell theory (may use RNA instead of DNA).

Eukaryotic cell

Contain a true nucleus and organelles.

Organelle

Usually membrane bound suspended in semi fluid cytosol.

Cytosol

Allows for the diffusion of molecules throughout the cell.

Nucleus

Genetic material encoded as DNA and organized into chromosomes.

Nuclear Membrane/Envelope

A double membrane that maintains a nuclear environment separate and distinct from the cytoplasm.

Nucleus Pores

In the nuclear membrane allows selective two way exchange of material between the cytoplasm and nucleus.

Genes

Coding regions in DNA

Histones

Organizing proteins in which DNA is wound around, then further wound into chromosomes.

Nucleolus

Subsection of the nucleus where ribosomal RNA (rRNA) is synthesized.

Mitochondria

Power plant of the cell.

Mitochondria contains…

1. Outer membrane.

2. Inner membrane

3. Cristae.

4. Intermembrane space

5. Matrix.

Outer membrane of mitochondria

Serves as a barrier between the cytosol and the inner environment of the mitochondrion.

Inner membrane of mitochondria

Arranged into cristae and contains the molecules and enzymes of the electron transport chain.

Cristae

Highly convoluted structures that increase the surface area available for electron transport chain enzymes in the mitochondria.

Inter membrane space of the mitochondria

Space between the inner and outer membranes.

Matrix

Space inside the inner membrane of the mitochondria.

Mitochondria are semi autonomous

They contain some of their own genes and replicate independently of the nucleus via binary fission.

Cytoplasmic/Extranuclear Inheritance

The transmission of genetic material independent of the nucleus.

Apoptosis

Programmed cell death. Can be caused by the enzymes of the mitochondria or lysosomes.

Mitochondria can keep the cell alive but also…

Killing the cell by release of enzymes from the electron transport chain. Kickstarts apoptosis.

Lysosomes

Single membrane bound structures containing hydrolytic enzymes that are capable of breaking down many substrates. (Substances ingested my endocytosis and cellular waste products).

Endosomes

Transport, package, and sort cell material traveling to and from the membrane. Functions in conjunction to lysosomes.

Where Endosomes can transport

Trans-golgi, cell membrane, lysosomal pathways for degradation.

Autolysis

Release of enzymes that leads to the degradation of cellular components.

Endoplasmic Reticulum (ER)

Series of interconnected membranes that are actually contiguous with the nuclear envelope.

Has a double membrane folded into complex structures with a central lumen.

Rough ER

Studded with ribosomes, which permit the translation of proteins destined for the secretion directly into its lumen.

Smooth ER

Lacks ribosomes and utilized primarily for lipid synthesis (phospholipids in cell membrane) and the detoxification of certain drugs and poisons.

Transports proteins from the RER to the Golgi.

Golgi apparatus

Stacked membrane bound sacs. Modify (addition of groups like carbs, or introduce signal sequences), sorted, and repackaged (in vesicles). Directed to correct location.

Exocytosis

When secretory vesicles merge with the cell membrane and releases its contents (Usually when product from Golgi is destined for secretion)

Peroxisomes

Contain hydrogen peroxide. Breakdown very long fatty acid chains via B-oxidation.

Participates in the synthesis of phospholipids and contain some of the enzymes involved in the pentose phosphate pathway.

Cytoskeleton

Provides structure to the cell and helps to maintain shape. Also provides a conduit for the transport of materials around the cell. Has three components.

Three components of cytoskeleton

Micro filaments, microtubules, intermediate filaments.

Microfilaments

Made of solid polymerized rods of actin. Actin organized into bundles and networks, providing protection by resisting compression and fracture.

Microtubules

Hollow polymers of tubulin proteins. Radiate thru cell providing pathways along which motor proteins like lines in and dynein carry vesicles.

Cilia

Composed of microtubules, projections from a cell that are involved in the movement of materials along the surface of the cell. (Line respiratory tract and movement of mucus)

Flagella

Structures involved in the movement of the cell, composed of microtubules.

9+2 structure

Composed of nine pairs of microtubules forming an outer ring with two microtubules in the center. Cilia and flagella share this structure and seen only in eukaryotic organelles of motility.

Centrioles found in Centrosome

Organizing centers for microtubules and are structured as nine triplets of microtubules with a hollow center.

Intermediate Filaments

Diverse group of filamentous proteins involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton. Includes keratin, desmin, vimentin, and lamins.

Intermediate filaments functions

• cell-cell adhesion or maintenance of the integrity of the cytoskeleton.

• Withstand tremendous amount of tension, increasing structural rigidity of the cell.

• Help anchor organelles including the nucleus.

Epithelial, Connective, Muscle, Nervous

Four tissue types.

Epithelial Tissues

Cover the body and line its cavities providing a means for protection against pathogen invasion and desiccation. Can be involved in absorption, secretion, and sensation. Highly diverse.

Basement Membrane

Underlying layer of connective tissue in which epithelial cells are tightly joined to each other to remain as one cohesive unit.

Parenchyma

Functional part of the organ made up of epithelial cells.

Epithelial cells often polarized

One side faces a lumen (hollow inside of organ or tube) or the outside world, while the other side interacts with underlying blood vessels and structural cells.

Simple, stratified, pseudostratified epithelia

Names of the number of layers of epithelia

Simple epithelia

One layer of cells

Stratified epithelia

Multiple layers of cells

Pseudostratified epithelia

Appear to have multiple layers of cells due to differences in cell height but are only one layer.

Cuboidal, columnar, squamous

Name for chapter of epithelia

Cuboidal

Cells are cube shaped

Columnar

Cells are long and thin

Squamous

Cells are flat and scale like

Connective tissue

Supports the body and provides framework for the epithelial cells to carry out their functions.

Stroma

Support structure, connective tissues are the main contributor to this.

Examples of connective tissue

Bone, cartilage, tendons, ligaments, adipose tissue, and blood.

Extracellular Matrix

Most cells in connective tissue produce and secrete materials such as collagen and elastin to form this.