Chapter 2: Cells- Lecture 1

Cells are the units of life and comprise the human body. Inherited traits and illnesses can be understood at the cellular and molecular levels

All cells share certain features, but they are also specialized because they express different subsets of genes.

Somatic (body) cells are diploid and sperm and egg cells are haploid. Stem cells produce new cells.

A prokaryotic cell is small and does not have a nucleus or other organelles. A eukaryotic cell has organelles, including a nucleus

Cells consist primarily of water and several types of macromolecules: carbohydrates, lipids, proteins, and nucleic acids

Organelles sequester related biochemical reactions, improving the efficiency of life functions and protecting the cell. The cell also consists of cytoplasm and other chemicals

The nucleus contains DNA and a nucleolus, which is a site of ribosomes synthesis. Ribosomes provide scaffolds for protein synthesis; they exist free in the cytoplasm or complexed with the rough endoplasmic reticulum (ER).

In secretion, the rough ER is where protein synthesis starts. Smooth ER is the site of lipid synthesis, transport, and packaging, and the Golgi apparatus packages secretions into vesicles, which exit through the plasma membrane. Lysosomes contain enzymes that dismantle debris (autophagy), and peroxisomes house enzymes that perform a variety of functions. Enzymes in mitochondria extract energy form nutrients.

The plasma membrane is a protein- studded phospholipid bilayer. It controls which substances exit and enter the cell (signal transduction), and how the cell interacts with other cells (cell adhesion)

The cytoskeleton is a protein framework of hollow microtubules, made of tubulin, and solid microfilaments, which consist of actin. Intermediate filaments are made of more than one protein type.

Coordination of cell division (mitosis) and cell death (apoptosis) maintains cell numbers, enabling structures to enlarge during growth and development but preventing abnormal growth.

Mitosis proceeds in four stages. In prophase, replicated chromosomes consisting of two chromatids condense, the spindle assembles, the nuclear membrane break down, and the nucleolus is no longer visible. In metaphase, replicated chromosomes align along the center of the cell. In anaphase, the centromeres part, equally dividing the now unreplicated chromosomes into two daughter cells. In telophase, the new cells separate. Cytokinesis apportions other components into daughter cells.

Internal and external factors control the cell cycle. Checkpoints are times when proteins regulate the cell cycle. Telomere (chromosome tip) length determines how many more mitoses will occur. Crowding, hormones, and growth factors signal cells from the outside; the interactions of cyclins and kinases trigger mitiosis from inside.

In apoptosis, a receptor on the plasma membrane receives a death signal, which activates caspases that tear apart the cell in an orderly fashion. Membrane surrounds the pieces, preventing inflammation.

Stem cells self-renew, producing daughter cells that retain the ability to divide and daughter cells that specialize. Progenitor cells give rise to more specialized daughter cells but do not self-renew

A fertilized ovum is totipotent. Some stem cells are pluripotent, and some are multipotent. Cells are connected through lineages

The three source of stem cells are embryonic stem (ES) cells, induced pluripotent stem (iPS) cells, and adults stems cells

The cell cycle describes whether a cell is dividing (mitosis) or not (interphase). Interphase consists of two gap phases, when proteins and lipids are produced, and a synthesis phase, when DNA is replicated

Stem cell technology enables researchers to observe the origins of diseases and to devise new types of treatments

Ninety percent of the cells in a human body are microorganisms. They are our microbiome.

Different body parts house different communities of microbes.

Genes interact with the microbiome and with environmental factors to mold most traits.

The activities and abnormalities of cells underlie all inherited traits and illnesses because they are the fundamental units that make up the human body. All living tissue is comprised of cells, and different kinds of organisms are classified by the kinds of cells they have.

Archaea, bacteria, eukaryotes. Achaea and bacteria do not have nuclear membranes. They still contain genetic material (of course!) but is is not enclosed within a nucleus. Archaea and bacteria are actually different kinds of organisms despite this overall similarity. Eukaryotes are everything else-plants, animals, amoebae, you name it. Eurkaryotes all have a membrane around the nucleus.

Carbohydrates(sugars and starches), lipids (fats and oils), proteins (enzymes), nucleic acids (building blocks of DNA), Vitamins, minerals. These are all macromolecules, large chemical structures. Within a cell, the macromolecules combine with each other form even larger structures within cells, such as the membrane surrounding the cell (plasma membrane). These components all have a purpose inside the cell. The components are important because a lack or excess of these components in your body can be devastating. We will talk about several illnesses related to the components of cells.

- a double layer of lipids in which proteins are embedded- this membrane is often referred to as a phospholipid layer. This is because it is composed of a phosphate linked to two chains of lipids. This type of molecule self assembles into a layer, with the water-loving (hydrophilic) phosphate group on one side, and the waterfearing ( hydrophobic) lipid chains on the other. It forms a double layer in this way. Some things can go through the membrane- small, non-charged molecules (including some medicines), but many other kinds of molecules cannot freely diffuse through the membrane (usually because they are too large, or too positively or negatively charged). However, charged molecules ( also called ions, like Na+, K+, Cl-, Ca2+) can go through the membrane by passing through channels that are created by proteins passing through channels that are created by proteins embedded in the plasma membrane. In this way, cells control what goes in and comes out.

-Eukaryotic cells also contain a membrane bound nucleus bound nucleus where the genetic material such as DNA is stored

-Cytoplasm: everything between the plasma membrane and the nucleus. Within cytoplasm, "organelles" carry out particular functions that help the cell survive and carry out its role in the body.

they are formed from phosphates and lipids in a double layer that surrounds all cells, and the nucleus in human cells. Allows control over what enters and exits a cell.

It contains chromosomes, which are made of DNA, the genetic material of the cell, and hence determine phenotype.

It is the site of protein synthesis; a template created from the DNA is transported to the ER, where a protein is synthesized from its bases.

Where proteins are modified here (sugars added) and prepared for secretion or transport to membrane.

It is a membrane-bound vesicle containing enzymes that can degrade food, proteins, other cellular components for re-use.

It provides energy for the cell from food through a series of biochemical reactions.

It provides structural support and flexibility, thus determining a cell's shape and impacting function.

A.) 50 Million

B.) 2 Billion

C) 50 Billion

D.) 240 Billion

E.) 37.2 Trillion

A.) 1

B.) 10

C.) 50

D.) 100

E.) 200+

A.) True

B.) False

A.) Chimp

B.) Human

C.) Drosophila

D.) Amoeba

E.) Arabidopsis

A.) Chimp

B.) Human

C.) Drosophila

D.) Amoeba

E.) Arabidopsis