Excelsior Biology Unit 5


A picture that shows the complete set of chromosomes grouped together in pairs, arranged in order of decreasing size. Normal humans have 23 pairs or 46 chromosomes.

Sex Chromosomes

Two of the 46 total chromosomes in the human genome are the sex chromosomes which determine gender. Females have two copies of the X chromosome and males have one X and one Y chromosome.

Pedigree charts

A chart that shows the relationships within a family. It can show the presence or absence of a trait according to the relationships between parents, siblings, and offspring. In the chart, the males are squares, females are circles. Parents are connected to their offspring by vertical lines , siblings and spouses are connected by horizontal lines. A Shaded circle or square indicates the expression of a trait, and an un-shaded circle or square indicates that the person does not express that trait.

Changes to the DNA sequence

Changes in a gene's DNA sequence can change proteins by altering their amino acid sequences, which may directly affect one's phenotype. In other words, there is a molecular basis for genetic disorders.

Cystic Fibrosis

A life-threatening, genetic disease that causes persistent lung infections and progressively limits the ability to breathe.
In people with CF, a defective gene causes the protein CFTR to not work correctly and instead produce a thick, buildup of mucus in the lungs, pancreas and other organs. In the lungs, the mucus clogs the airways and traps bacteria leading to infections, extensive lung damage and eventually, respiratory failure. In the pancreas, the mucus prevents the release of digestive enzymes that allow the body to break down food and absorb vital nutrients.

Sickle Cell

An inherited blood disorder that affects the red blood cells. The hemoglobin in the Red Blood Cells is an abnormal type. There is one advantage for someone who carries the disease but doesn't have the disease (one sickle cell allele) and that is that they are more resistant to malaria than the average person.

Restriction Enzymes

Enzymes that cut DNA in a particular place. These highly specified substances cut even the largest DNA molecule into precise pieces that are several hundred bases in length.

Gel Electrophoresis

Laboratory technique used to separate macromolecules based on size. This will even separate DNA fragments.


The biological studies that use computer programs as part of their methodology. The field of study in molecular biology referring to the creation, development and operation of databases and other computing tools to collect, organize and interpret data.

Selective breeding

Also known as artificial selection, this process includes breeding in order to obtain specific traits. This process includes hybridization as well as inbreeding. Humans use selective breeding, which takes advantage of naturally occurring genetic variation, to pass wanted traits on to the next generation of organisms.


The genetic heritable condition of possessing more than two complete sets of chromosomes. This happens most often in plants. These change the number of chromosomes thereby creating a new species. Polyploidy is usually fatal in animals, but for some reason, plants are much better at tolerating the change in the number of chromosomes and thrive.

Finding genes

Scientists have been trying to identifying the specific genes for certain purposes in different species. They need to know the DNA sequence in order to find and study that gene. They use a process called Southern blotting to find the genes.

Recombinant DNA

Scientists have discovered how to create DNA molecules in the lab from different sources and they can insert those molecules into living cells. These molecules are known as recombinant DNA. Scientific breakthroughs in this field have had affect in medical research and in preventing and treating diseases.

Transgenic Organisms

Organisms that contain genes from other species. Transgenic organisms can be produced by the insertion of recombinant DNA into the genome of a host organism. They can be both plants and animals.

Gene Therapy

An experimental field of genetics that practice the process of changing a gene to treat a medical disease or disorder.

DNA fingerprinting

DNA fingerprinting analyzes sections of DNA that may have little or no function but that vary widely from one individual to another.

Ethics of the New Biology

Just because we have the technology to modify an organism's characteristics, are we justified in doing so? It seems easy to agree that we should use our technology to cure and prevent disease, but the next step is to attempt to engineer plants, animals including humans with certain traits or abilities. This raises the question of whether or not we should do these things just because we can.

GM Foods (Genetically Modified)

Food that has had their DNA altered through genetic engineering. The Pro's of GM foods are that higher yields are crops are produced, reduced land and energy resources devoted to agriculture, and a lower cost of food. Cons of GM foods include the insect resistance could kill beneficial insects along with pests, the death of the small farm, and possible health concerns.


A nonliving particle made of proteins, nucleic acids, and sometimes lipids. They can reproduce only by infecting living cells.


The protein coat surrounding a virus.


Viruses that infect bacteria only and literally mean "bacteria eaters.


Bacteriophage DNA that becomes embedded in the bacterial host's DNA. It may remain part of the DNA of the host cell for many generations.

Bacteria and Archaea

Prokaryotes are classified as either bacteria or archaea. These are two of the three domains of life. Bacteria and Archaea look very similar under the microscope. Both are equally small, lack nuclei, and have cell walls. There are important differences, however. The walls of archaea lack peptidoglycan and their membranes contain different lipids. Also, the DNA sequences of archaea genes are more like eukaryotes than bacteria.

Structure of Bacteria

Bacteria have a long whiplike tail for movement called a flagellum as well as hair like pili which serve to anchor the bacterium to a surface.

Prokaryotic Shapes

There are three shapes of prokaryotes. Rod-shaped prokaryotes are called bacilli, spherical prokaryotes are called cocci, and spiral or corkscrew shapped prokaryotes are called spirilla.


Disease-causing agents that can come from any taxonomic group, but bacteria and viruses are among the most common. All currently known prokaryotic pathogens are bacteria.

Viral Diseases

Viruses cause disease by directly destroying living cells or by affecting cellular processes in ways that upset homeostasis. These include the common cold, influenza, AIDS and HIV, chicken pox, Hepatitis B, West Nile Virus, and HPV. Influenza includes body aches, dry cough, fatigue, and congestion. AIDS and HIV destroys helper T-cells. Hepatitis B includes jaundice, abdominal pain, nausea and vomiting. West Nile is similar to influenza without the cough and congestion. HPV includes genital warts or cancer of the reproductive organs.