Notes, summaries, assignments, exams, and problems for Biology

The Excretory System

Organs Involved

• Kidneys: Eliminate toxic substances from metabolism through urine.
• Lungs: Expel CO2 derived from cellular respiration.
• Liver: Bile helps to eliminate waste through feces.
• Sweat Glands: Responsible for sweat excretion.

The Urinary System

Kidneys

• Two organs located at the back of the abdomen.
• Involved structures: Renal artery and vein.
• Primary function: Produces urine.

Urinary Tract

• Ureters
• Bladder
• Urethra

Kidney Structures

• Renal Artery: Carries blood with waste to each kidney.
• Renal Vein: Carries filtered blood away from the kidneys.

The purpose of sexual reproduction is to produce offspring through the fusion of female and male gametes from two individuals (fertilisation).

Asexual reproduction, where a plant can reproduce without involving another plant, is possible in hermaphrodites, which have both male and female organs.

Pollination: Pollen grains travel from the flower to the other plant by wind or by animals.

Fertilisation: When a pollen grain reaches the stigma, the male gamete joins with the female gamete.

Seed Formation: The zygote develops and then grows into a new plant.

Fruit Formation:

1. Biological Interaction

The interaction function enables organisms to receive changes and stimuli from their environment.

1.1 Stages of Interaction

The interaction function is divided into three stages: perception of stimuli, processing of information, and generation of a response.

• Stimulus: A physical or chemical change that affects the body.
• Receptors: Specialized cells that receive stimuli and transmit information.

Types of Receptors:

• Internal: Perceive changes inside the body.
• External: Perceive changes outside the body.
• Mechanoreceptors: Perceive mechanical stimuli.
• Thermoreceptors: Perceive changes in temperature.
• Nociceptors: Perceive pain.
• Photoreceptors: Perceive changes in light.

1.2 Coordination Centers

Coordination centers receive information... Continue reading "Biological Interaction: Perception, Coordination, and Senses" »

Understanding Key Human Muscles and Their Functions

Temporalis

• Origin: Along temporal lines of the skull.
• Insertion: Coronoid process of the mandible.
• Action: Elevates the mandible.

Masseter

• Origin: Zygomatic arch.
• Insertion: Ramus of the mandible.
• Action: Elevates the mandible and closes the jaw.

Sternocleidomastoid

• Origin: Attaches to the sternal end of the clavicle and manubrium.
• Insertion: Mastoid region and lateral nuchal line of the skull.
• Action: Flexes the neck.

Pectoralis major

• Origin: Cartilage of ribs 2-6, sternal body, and medial clavicle.
• Insertion: Greater tubercle and intertubercular groove of the humerus.
• Action: Flexion, adduction, and medial rotation at the shoulder.

Biceps brachii

• Origin: Coracoid process of the scapula.
• Insertion: Tuberosity

Eukaryotic Cell Organelles: Structure and Function

Cell Membrane

All cells are covered by the cell membrane. It supports and protects the cell, forming a barrier between the cell and its environment. It also controls the movement of materials into and out of the cell, helping to maintain homeostasis.

Cell Wall

The Cell Wall is found only in plant cells and is primarily made of cellulose. Its functions include:

• Providing structural support and protection.
• Allowing the diffusion of gases into and out of the cell.

The strength provided by the cell walls enables plants, such as trees, to stand tall and grow against gravity.

Nucleus

The Nucleus is a spherical, membrane-bound organelle. It directs most of the cell's activities and contains the cell's hereditary

Sintesis is called like that cause dna sts is taking place. Daughter cell trought mitsis=46. Cancer spend less time in interphase. Dna replication in interphase. Growth cell in g1. Cell g0= cerebral cortex. Most cells spend in interphase. Divide and dont die cancer. Function and decide typr of cell=differentation. Human sommatic= 46 crhomo  crossing over meiosis mix genes. Half crhomo=haploid. Full=diploid. No stem cell =gamete stem cell. Mult 100-150 cells embryonic stem cell. Tissues cells adult stem cell. Stem is medical because is undiferentiated. Sperm cells meiosis. Overall meiosis to make 4 unike haploid from a diploid. Meiosis only occurs in reproductive organs. Homozygous=pair. Observable traits=phenotype. Allele pairs=genotype. Crossing... Continue reading "Cell Biology, Genetics, and Evolutionary Theory Essentials" »

Structure of HIV Virus and Interaction of HIV with Target Cells and Involved Molecules

·Human immunodeficiency viruses 1 and 2 (HIV-1 and HIV-2)

·HIV-1 is more important (most common cause of AIDS)

·Member of the lentivirus family of animal retroviruses

Molecular Features

oTwo identical strands of RNA wrapped within a core of viral proteins p24, surrounded by a matrix of p17 proteins

o Phospholipid bilayer envelope derived from host cell membrane but including virally encoded membrane proteins gp41 and gp120

§ Proteins form a unit

§ gp41 is a transmembrane molecule and noncovalently associated to gp120 subunit, extruding out of the membrane

o Two very important enzymes in core: reverse transcriptase and proteinase

o Long terminal repeats (LTRs)... Continue reading "HIV Structure, Viral Lifecycle and Target Cell Interactions" »

Gene Regulation and Molecular Insights

Goal: To organize gene orientation and understand gene regulation involving 25,000 Protein-Coding Genes (PCG) and 40,000 non-coding RNA (ncRNA) to advance knowledge and medical insight.

Key Mechanisms of Gene Expression

• 3D Chromosome Territories: mRNA looping and open chromatin.
• Epigenetic Marks:
  • Little to no methylation on DNA.
  • Histone marks.
  • Chromatin modification coactivator complexes and ncRNA coactivators.
• Transcription Factor Activators: Usually heterodimers.
  • Transactivation Domain (TD): Interacts with the mediator.
  • Binding Domain (BD): Binds to DNA.
• RNA Polymerase and Factors at the Promoter:
  • Elongation process.
  • Production of multiple mRNA molecules.
  • Presence of many promoters.
• Maternal and Paternal Expression:

Essential Terminology in Human Anatomy and Physiology

Skeletal System and Musculature

• Scapula: A flat, triangular bone that forms the back of the shoulder.
• Tibia: The inner bone of the lower leg.
• Femur: A bone in the leg extending from the pelvis to the knee.
• Ulna: The bone in the forearm located on the side opposite the thumb.
• Radius: The bone in the forearm located on the side of the thumb.
• Humerus: The long bone in the arm running down from the shoulder to the elbow.
• Skull: The bones of the head, which surround the brain and give the head its shape.
• Pelvis: The bones below the abdomen that support the lower back and are connected to the bones of the leg.
• Hip: The joint and surrounding region connecting the leg to the trunk.
• Deltoid: A large muscle