RNA, Genes and Protein Synthesis

RNA (Ribonucleic Acid)

• A nucleic acid essential for biological functions.
• Functions as biological function or a template to create proteins via translation.
• RNA has a single helix structure, unlike the double helix of DNA.
• RNA does not contain Thymine (T), which is replaced by Uracil (U).

Genes and Protein Synthesis

• Genes serve as the functional units of heredity.
• DNA carries gene segments responsible for protein production.
• Proteins determine bodily traits like eye and hair color, blood type, and height.
• Genes act like switches, being turned on or off as needed.
• Specialized cells are programmed to perform specific functions.
• Genes dictate the necessary proteins for cells to produce.
• Proteins define an organism's characteristics.

Proteins

• Enzymes are proteins accelerating reactions in the stomach and small intestines during digestion.
• Hemoglobin is an oxygen-carrying protein in red blood cells providing blood its color.
• Hormones are proteins that regulate growth, development, metabolism, and sleep.
• Keratin forms the outer layers of hair, nails, and skin.
• Collagen builds skin, muscles, bones, tendons, and ligaments.
• Protein channels in the cell membrane facilitate substance entry and exit.

Protein Synthesis

• Cells create proteins from DNA through protein synthesis.
• Transcription and translation are the two steps in the synthesis

Transcription

• Transcription occurs in the nucleus.
• mRNA communicates with ribosomes.
• RNA polymerase binds to a gene's promoter region, signaling DNA to unwind.
• RNA polymerase "reads" the unwound DNA and constructs mRNA using complementary base pairs
• Adenine in DNA binds to Uracil in RNA during transcription.
• RNA polymerase reaches a stop sequence, mRNA detaches, and leaves the nucleus for the cytoplasm.

Genome

• The genome comprises the total DNA within an individual.
• The genome resides in the cell nucleus and includes 46 chromosomes.
• The genome contains all genetic information for an individual's development and function.

Karyotype

• A karyotype is an image of an individual's complete set of chromosomes
• Karyotypes help observe chromosomal changes and determine disorders.
• Humans have 46 chromosomes, which is double the amount of individual chromosomes(23).
• There are 22 pairs of autosomal chromosomes.
• Chromosomes are identified by scientists using size, banding pattern.
• Karyotypes can be collected using amniotic fluid, chorionic villi, or bone marrow samples.

Cell Division

• Eukaryotic cells undergo division for growth, repair, or creation of more cells.
• Mitosis (body cells) and Meiosis (sex cells) are the two types of division.
• Somatic cells divide into two identical daughter cells via mitosis for growth and repair.
• Each new cell contains 46 chromosomes.

Cell Division - Interphase

• The cell spends most of its time in interphase.
• The cell grows and replicates chromosomes in preparation for division.
• The cell exists interphase and begins mitosis

Cell Division - Prophase

• Prophase causes the nuclear membrane to break down.
• Centrioles create microtubule spindles to organize and move chromosomes.

Cell Division - Metaphase

• Chromosomes align at the cell's equator.
• Spindles attach to chromosome centromeres.

Cell Division - Anaphase

• Spindles pull chromosomes to opposite sides of the cell.
• Ensures correct DNA distribution.

Cell Division - Telophase

• Chromosomes are positioned at opposite ends/poles.

Cell Division - Cytokinesis

• Cytokinesis divides the cell into two, creating two identical new cells.
• Differs between animal and plant cells.

Cell death

• Unneeded or harmful cells are destroyed via programmed cell death.
• Apoptosis, an intracellular death program, removes irreparably damaged cells.
• Apoptosis failure from gene mutations or deletions can cause uncontrolled cell division and tumors.
• Tissue or organ cell death can result from injury, lack of oxygen, infection, or radiation.

Meiosis

• Meiosis divides gametes (sex cells), yielding four unique cells for reproduction.
• One cell divides twice, creating four cells with half the original genetic information.

Patterns of Inheritance

• Alleles, identified by letters, are alternative forms of a gene.
• An example is eye color genes with possible alleles for blue, brown, or green.
• Dominant alleles, such as (B) for brown eyes, override other alleles, resulting in easily expressed traits (BB or Bb).
• Recessive alleles, such as (b) for blue eyes, require two copies (bb) to be expressed.

Genetics

• Genotype refers to the genetic composition inherited from parents.
• Phenotype is an organism's physical appearance.
• Homozygous dominant: BB brown eyes
• Homozygous recessive: bb Blue eyes
• Heterozygous: Bb Brown eyes.

Punnett Square

• A Punnett square determines offspring's theoretical traits from a cross.