PLTW Biomed 2.2.1-2.2.3

MRI (magnetic resonance imaging)

A medical imaging technique that uses magnetic fields and radio waves to take pictures of the soft tissues of the body.

Differential diagnosis

Many conditions share similar symptoms and few are easily identifiable by a single test. As a doctor goes through the diagnostic process, they look at an individual’s medical history, current symptoms, and the results of physical exams, routine testing, and blood work. They then develop a list of possible diseases or disorders based on this information. The doctor uses this information to plan the next steps including what further testing should be done. This process helps rule out possible conditions and works toward a final diagnosis of the cause of a patient’s symptoms. 

Eukaryotic cells

Organisms that have membrane-bound organelles.

Somatic cells

Any cell in the human body that is not a sex cell (egg or sperm).

Mitosis

A process that takes place in the nucleus of a dividing cell. Mitosis involves the doubling and separation of genetic material and results in the formation of two new nuclei, which each have the same number of chromosomes as the parent nucleus.

Chromosomes

Tightly coiled DNA that is found in the nuclei of cells

Homologous

Chromosome pairs, one from each parent, having similar gene composition, size, and structure.

Chromatids

One half of a chromosome.

Centromere

the centralized region joining two sister chromatids.

Interphase (Mitosis)

DNA replicates so that there are two copies of each chromosome. each identical copy is referred to as a sister chromatid

Prophase

Chromosomes condense and become visible under a light microscope, and they pair up with their sister chromatids. The mitotic spindle forms, and the nuclear envelope disappears.

Metaphase

Chromosomes line up at the center (middle) of the cell. Fibers attach to each of the sister chromatids and will pull each chromatid to opposite poles of the cell.

Anaphase

Each chromosome separates and the sister chromatids are pulled to the opposite poles of the cell.

Telophase and cytokinesis

The cell splits into two. Each new “daughter cell” looks identical to the original cell.

What happens when cell division goes wrong?

In mitosis goes unchecked and leads to uncontrolled cell division. The cause of this error usually links to mistakes made during DNA replication in interphase. These mistakes result in mitosis being sped up or permanently turned on, causing cells to quickly or continuously replicate and divide. When cells divide uncontrollably, tumors, masses of extra cells, can form. 

Benign

Benign tumors are those that are generally considered harmless. They will not spread to other parts of the body or invade other tissues and are not cancer. 

Malignant

Malignant tumors are also known as cancerous tumors. These tumors are harmful and can invade other tissues or spread to other parts of the body if not treated. This spread is called metastasis.

Cancer

A disease caused when cells divide uncontrollably and spread into other tissues.

Metastasis

The spread of cancerous cells to other tissues or parts of the body.

Biopsy

The removal of cells or tissues from a patient’s body using a needle, scalpel, or other tools to study them more closely using a microscope ( in order to determine whether a tumor is benign or malignant)

Pathologist

A pathologist is a medical professional who examines bodies, tissues, and fluid samples to look for changes or other signs of disease and collaborate with other healthcare providers to diagnose patients.

Gene

A sequence of nucleotides that codes for a protein, resulting in a specific phenotype.

Mutation

A rare change in genetic material, which ultimately creates genetic diversity within a species.

Nucleotide

A building block of DNA that consists of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group. (A, T, C, G)

RNA (ribonucleic acid)

A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U). RNA is usually single stranded and functions in protein synthesis and as the genome of some viruses

Protein synthesis

The creation of a protein from a DNA template

DNA

Deoxyribonucleic acid; A type of nucleic acid consisting of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T). DNA is double-stranded and helical and functions in protein synthesis and as the genome of some viruses; capable of carrying all the instructions necessary to code for all of the proteins that make life possible

mRNA

Messenger RNA, a type of RNA that is transcribed from DNA and translted by ribosomes in the cytoplasm to produce proteins

Codon

A sequence of three nucleotides found in DNA or mRNA, that code for a specific amino acid or stop signal

Amino acid

One of a group of compounds that, when linked in a chain with other amino acids, forms a protein.

Transcriptions and translation

The synthesis of RNA from a DNA template; The synthesis of protein using the genetic information encoded in mRNA.

Genome

A complete set of the genes in one organisms

Geneticist

Someone who studies genes and gene inheritance, compares the gene sequences from the patient to the gene sequences for known healthy genes. They then draw conclusions related to the patient’s genetic health.

Substitutions

One DNA base is exchanged for another, such as switching an A to a G.

Proteins

A type of biomolecule and are the primary building blocks of all life; they are the most abundant biomolecules present in living cells

(Functions of proteins) Cellular reactions

Digestion, biosynthesis, controlling cell growth and division

(Functions of proteins) Providing Defense

Defensive proteins (eg. antibodies) combat foreign invaders to the body. These invaders include bacteria, viruses, fungi, pollen, and others.

(Functions of proteins)Building structures

Silk fibers (spider webs); Collagen and elastin (animal connective tissue; Keratin (feathers and hair)

(Functions of proteins) Transporting materials

-Carry essential nutrients and gasses through the body

-carry cellular waste for disposal

(Functions of proteins) Coordinating Cellular Activities

-Hormonal proteins help maintain homeostasis. For example, the protein insulin helps regulate blood glucose levels.

-Sensory proteins are used to interpret our environment (taste, smell, sound).

(Functions of proteins) Movement

Motor and contractile proteins, such as actin and myosin, found in muscles and used during cell division, help cells move.

Variety of mutations and what happens to codons

-Swapped, added, deleted

-Single base pair change (substitution/point mutation): one DNA base is exchanged for another

-Insertion: one DNA base is inserted into a gene sequence

-Deletion: one DNA base is deleted from a gene sequence

How are proteins made?

Within a cell, DNA is housed in the nucleus. When a protein needs to be made, a signal is sent to a cell to turn on the gene that codes for the needed protein. This is the start of transcription. Transcription occurs inside the nucleus. During transcription, DNA is read by an enzyme called DNA polymerase and produces messenger RNA, abbreviated mRNA. This newly created mRNA molecule moves to the cytoplasm where the process of translation can occur. During translation, small organelles called ribosomes read the mRNA sequence. These organelles direct transfer RNA, or tRNA, to assemble a specific sequence of amino acids. A codon is a sequence of three mRNA bases that codes for one amino acid. When all the amino acids coded for by a gene link, they fold, and this creates a functional protein.

Genotype

All or part of the genetic constitution of an individual or group

Phenotype

The physical and physiological traits of an organism that are determined by the organism’s genetic makeup

Alleles

Any of the alternative forms of a gene that may occur at the same place on a chromosome

Dominant

A genetic trait is dominant if the associated phenotype is seen in an individual who only has one copy of the gene associated with the trait

Recessive

A trait that is evident only when an organism inherits two copies of a recessive allele for a specific gene

Homozygous

Having two identical alleles at one location on two homologous chromosomes

Heterozygous

Having two different alleles at one location on two homologous chromosomes

Pedigree

A diagram that shows the occurrence of phenotypes through several generations of genetically related individuals. Symbols are used to represent each individual. (square male, circle female)

Autosomal recessive

Two mutated alleles are required for the individual to experience disease symptoms. If a patient inherits only one mutated allele, the other dominant allele compensates, and the individual does not experience symptoms. Autosomal recessive traits pass from both parents onto their child.

Autosomal dominant

One mutated allele is sufficient to cause symptoms in the individual. The mutated allele is considered dominant, because the disease trait(s) are experienced with one dysfunctional allele. Autosomal dominant traits pass from one parent onto their child.