Studying

DNA, RNA, and Proteins

• DNA:

  • Double-stranded helix

  • Contains genetic information

  • Made up of nucleotides (A, T, C, G)

  • Replicates during cell division

• RNA:

  • Single-stranded molecule

  • Transcribed from DNA

  • Messenger RNA (mRNA) is a type of RNA that carries genetic information from the DNA in the nucleus of a cell to the ribosomes, where it is translated into a specific protein. The mRNA molecule is synthesized during the process of transcription, where a section of DNA is copied into RNA by the enzyme RNA polymerase. The mRNA molecule is then transported out of the nucleus and into the cytoplasm, where it is translated by the ribosomes.

  • Transfer RNA (tRNA) is another type of RNA that plays a critical role in protein synthesis. It is responsible for carrying amino acids to the ribosomes, where they are assembled into a protein chain. The tRNA molecule has a specific sequence of nucleotides that allows it to recognize and bind to a specific amino acid. Once the tRNA molecule has bound to the amino acid, it can then transport it to the ribosome, where it is added to the growing protein chain.

  • Ribosomal RNA (rRNA) is the third type of RNA that is involved in protein synthesis. It is a component of the ribosome, which is the cellular machinery responsible for assembling proteins. The rRNA molecule helps to catalyze the formation of peptide bonds between amino acids, which is a crucial step in the process of protein synthesis.

  Proteins:

  • Made up of amino acids

  • Perform various functions in the body

  • Can be enzymes, hormones, or structural components

  • Folding is crucial for the function

    • the physical process by which a linear polypeptide folds into its characteristic and functional three-dimensional structure

Genetics → Mendel

• Father of Genetics: Gregor Mendel

• Discovered laws of inheritance

  • Law of Segregation

    • only one of the two gene copies present in an organism is distributed to each gamete that it makes, and the allocation of the gene copies is random

  • Law of Independent Assortment

• Law of Segregation

  • alleles separate during gamete formation

• Law of Independent Assortment

  • genes for different traits are inherited independently

• Mendelian inheritance patterns

  • Dominant inheritance (RR x rr → __R__r)

    • A single copy of a gene is enough to produce a particular trait.

  • Recessive inheritance (rr x rr → rr)

    • An individual must inherit two copies of a recessive allele in order to express a particular trait.

  • Codominant inheritance

    • Both alleles in a heterozygous individual are expressed equally.

    • Red + White = Red & White

  • Incomplete dominance

    • Neither allele in a heterozygous individual is completely dominant over the other.

    • Red + White = Pink

• Punnett square

  • predicts offspring genotype and phenotype

• Mendelian genetics laid the foundation for modern genetics.

Meiosis → Making Gametes

• Meiosis is a type of cell division that produces gametes (sex cells).

• It involves two rounds of cell division, resulting in four haploid cells.

• The process includes crossing over and independent assortment, which increase genetic diversity.

  • Crossing Over - genetic material is swapped between two chromosomes

  • Independent Assortment - the allele a gamete receives for one gene does not influence the allele received for another gene

• Meiosis occurs in the gonads (ovaries and testes) of sexually reproducing organisms.

Evolution

• Darwin’s voyage and discoveries led to his theory of evolution

  • Patterns of diversity

    • Species vary globally

    • Species vary locally

    • Species vary over time

  • Influenced by Hutton and Lyell

    • Causes of long-ago changes are the same for current changes

  • Galapagos finches had different adaptations that better fit the needs of different areas

    • Natural selection favored those with the optimal beaks for their food

    • Eventually branched out to form their own species from the adaptations

• Natural Selection

  • the process by which organisms with traits that are better suited to their environment are more likely to survive and reproduce.

  • Required conditions

    • Reproduction - Entities must reproduce to form a new generation

    • Heredity - Offspring must tend to resemble their parents (Mendelian inheritance)

    • Physical Variation - Characteristics of members in the population must differ

    • Population Variation - The fitness of organisms must differ

• Evidence

  • Biogeography

    • Shows how organisms have changed over time, and how they have been distributed

  • Homologous Structure

    • Similar structures in different species

    • Inherited from a common ancestor

  • Analogous Structure

    • Different structures that serve the same function in different species

    • Evolved to do the same job, not from a common ancestor

  • Vestigial Structure

    • Structures that are no longer used

    • Remnants of structures used by an organism’s ancestors

  • Molecular evidence can be seen in similarities when comparing DNA

Immunity

Nonspecific/Innate Defense

1st Line (Prevent entry of pathogens)

• Skin → Most widespread nonspecific defense

  • Very few pathogens can penetrate the skin’s surface

• Mouth, Nose, Eyes, etc.

  • Saliva, mucus, and tears contain lysozyme

    • an enzyme that breaks down bacterial cell walls

  • Mucus in the nose and throat traps pathogens, then cilia push trapped pathogens away from the lungs

• Stomach acid destroys swallowed pathogens

2nd Line (If pathogens enter the body)

• Inflammatory Response

  • Infected areas become red and painful, or inflamed

  • Begins when pathogens stimulate mast cells to release histamines

    • increase flow of blood and other fluids to the affected area

  • Fluid leaks from expanded blood vessels, causing the area to swell

    • White blood cells enter infected tissues

      • Many are phagocytes that engulf and destroy bacteria

  • Response causes local temp increase → wounded area warmth

• Interferons

  • Proteins that inhibit viral synthesis, helping block viral reproduction → Interfere with viral growth

  • Slow down infection, buy time for specific immune defenses

• Fever

  • The immune system releases chemicals to increase body temp

  • Raised body temp may slow or stop some pathogen’s growth

  • Higher body temp also speeds up parts of the immune response

Specific/Adaptive Defense

• Can distinguish between “self” and “other”

• Deactivate or kill any foreign substance or cell that enters the body

• The immune system “remembers” specific invaders, allowing a quicker and more effective attack for repeated pathogens

• Specific immune defenses are triggered by antigens

  • any foreign substance that can stimulate an immune response, often located on the outer surfaces of bacteria, viruses, or parasites

  • The immune system responds by increasing either

    • cells that attack invaders directly

    • cells that produce antibodies

• Antibodies tag antigens for destruction by immune cells

  • may be attached to some immune cells, or free-floating in plasma

  • The body makes up to 10 billion different antibodies

  • The shape of each antibody allows it to attach to one specific antigen

• Lymphocytes are the main working cells of the immune response (B and T)

  • B lymphocytes (B cells) are produced and mature in red bone marrow

    • Have embedded antibodies, discover antigens in body fluids

  • T lymphocytes (T cells) are produced in bone marrow but mature in the thymus

    • Must be presented with an antigen by infected body cells or immune cells (Ones that wait around until someone finds them and lets them know that they specifically are needed)

  • Each B and T cell can recognize one specific antigen

  • A person’s genes determine particular B and T cells that are produced

  • When mature, B and T cells travel to lymph nodes and the spleen to encounter antigens