Cell Organelles and Immune System: Functions and Defenses

Posted on Feb 5, 2024 in Biology

TERM 1

Functons of organelles

• Cell membrane: Surrounds the cell and controls the exchange of materials.
• Cytoplasm: The liquid where organelles are suspended.
• Mitochondrion: Provides energy to the cell through cellular respiration.
• Ribosomes: Organelles that produce proteins.
• Endoplasmic reticulum: Network of sacs and tubules involved in protein and lipid production.
• Golgi apparatus: Modifies and packages proteins and lipids for export.
• Lysosomes: Vesicles with digestive enzymes for breaking down molecules and organelles.
• Cytoskeleton: Protein filaments that give shape to the cell and aid in cellular division.
• Centrioles: Structures involved in cytoskeleton organization and cellular division.
• Nucleus: Organelle containing DNA and controls cellular processes.

Active transport

a method by which particles are moved against a concentration gradient. Energy needed (ATP) involves protein in plasma membrane. Endocytosis (into the cell) and Exocytosis (out of the cell), active processes involving the bulk transport of materials trought the membrane.

Concept of Health

Healthy life is not life without disease, a health life presents well-being (physical, mental and social)

Infectious disease:

cause by other Living organism (pathogens as bacteria/virus), contagious. Ej: AIDS, Flu.

Non-Infectious disease:

many causes, not pathogen. No contagious. Ej: cancer, depression.

Healthy habits to prevent diseases:

Balance diet/ hydrate/ sleep.

Feeding is the process by wich those nutrients are obatined from the enviroment, while nutrition includes several processes that allow organism to transfor those nutrients so our cells can use them.

TERM 2

Immune system:

We have an immune system that helps us fight diseases. There are two types of defences:

External/Passive Defences:

• Physical barriers: Skin and mucus-secreting cells.
• Biochemical barriers: Enzymes in tears and stomach acid.
• Ecological barriers: Intestinal flora.
• Mechanical barriers: Mucus.

Internal/Active Defences:

• Phagocytes: Engulf and destroy pathogens through unspecific immune response.
• B-lymphocytes: Produce specific antibodies that recognize and bind to antigens on pathogens.
• Antibodies: Facilitate the destruction of pathogens by other cells.

Antibodies:

• Immune system proteins that target specific antigens.
• Attach to antigens and mark them for elimination.
• Incite immune reactions against diseases.
• Defend the body against infections and diseases.

Antigens:

• Substances that can trigger an immune response.
• Found on the surface of pathogens or non-pathogenic substances.
• When they enter the body, they stimulate the immune system to produce antibodies.
• Antibodies are produced to eliminate the antigens.

Lymphocytes:

• Type of white blood cell.
• B-cells: Produce antibodies.
• T-cells: Have various functions, including recognizing and eliminating infected cells, regulating immune responses, and assisting B-cells.

Tumor: a rise to a mass of abnormal cells: 2 types

• – Benign: self limited/not invasive/ no metastasise
• -Malignant/ cancer: cell divide no limit to other organs (metastasise)

Prevent infectious illnesses:

• healthy lifestyle
• vaccination: introducing dead microbes, to healthy organism (creates specifi defences). Produces antibodies against them.

How to cure them:

• Serum therapy: injection of antitoxins with antibodies produced by another person (tetanus/rabies)
• Drug therapy: chemical substances, or medicine. Drugs that act against microbes. (Antibiotics)
• Antibiotics: Antimicrobial substance, only agains bacteria and some fungi. Don’t take for viral infection. Prescribed by doctor.

Drug use: (3 consequences)

• short term health: intoxication from high levels of drugs in the body. Effects vary on the type and dosage, can include drunkenness, convulsions, coma, death… Alters perception of reality and increases the risk of accidents.
• Medium and Long: damage the nervous system, leading to dementia, psychosis, and behavioral disorders. Harm to the liver, respiratory system, and circulatory system. Injection drug transmit infectious diseases like HIV or hepatitis B.
• Social: cause problems in their family/work/studies.. becoming pest to society.

BIOMOLECULES

Carbohydrates: Source of energy for body and cells. Excess stored as glycogen and fats.

• Monosaccharides: simple crbh (glucose/fructose). Soluble in water, goes in blood, dissolve in cytoplasm.
• Polysaccharides: complex crbh (Mnosch, joined). Water insoluble, good storing energy. Ej: Starch/cellulose.

Lipids: fats. source energy. insoluble in water. store energy (adipose tissue). 3 fatty acids+1 molecule glycerol =Lipids

2 types: fats (solid), oils (liquid). Main component cell membrane, provide insulation.

Proteins: 50% dry cell mass in the body.

Function–> structural material, transport molecules, hormones, natural catalyst, defence agains diseases.

Made of aminoacids. 20 different (12 prduced by body, 8 provided by diet)

Nucleic acids: DNA and RNA, store/transmit genetic info. DNA carries instructions for build/maintain organism. RNA play role in protein synthesis.

2 DISEASES BC OF UN-HEALTHY DIETS

Obesity: too much body fat in adipose tissue under skin/ around organs. You eat more calories than use.

Diabetes/anorexia/bulimia: Poor diet.

Types of non-infectious diseases:

• Diseases affecting normal system functioning:
  • Coronary heart diseases
  • Respiratory diseases
• Traumatic diseases:
  • Sports injuries
  • Domestic, traffic, or work accidents
• Endocrine and metabolic diseases:
  • Excessive or deficient hormone secretion
  • Malfunctions in metabolic reactions
  • Examples: obesity, diabetes
• Deficiency diseases:
  • Caused by poor diet or lack of essential substances
  • Examples: anemia (iron deficiency)
• Psychological/mental disorders:
  • Abnormal behavior due to changes in brain function
  • Examples: schizophrenia, depression, anorexia, bulimia
• Genetic diseases:
  • Present at birth, caused by genetic disorders, hereditary diseases inherited from parents
  • Examples: certain types of blindness
• Cancer:
  • Uncontrolled and rapid cell division
  • Invasion and destruction of tissues
  • Metastasis to other parts of the body
  • Formation of abnormal cell masses (tumors)

TERM 3

Nucleic acids: macromolecules composed of monomers (Nucleotide). Viruses only 1 type of nucleic acid.

Nucleotides: composed 3 parts

1.Phosphate group                                 .  

2.Pentose –> Ribose (R) and Deoxyribose (D)

3.Nitrogenous base–> adenine (A), guanine(G), cytosine (c), Thymine (T) and Uracil (U). (+nucleotides=polynucleotide)

Concept DNA: 2 polynucleotides, form double helix. Strands complementary. Bases compatible: A-T / C-G

Function DNA/RNA:

DNA: important molecule, genetic material. component of chromosome. Gene portion DNA, particular hereditary character.

RNA: sigle-strand polynucleitide molecule. 3 types: ribosomal (rRNA), transfer (tRNA), messenger (mRNA). Help protein synthesis.

GENETIC INFORMATION

expressed bc of proteins, molecules carry out celular functions. Proteins synthesize in ribosome. (in the cytoplasm)

Protein synthesis carried out bc of : mRNA, tRNA, rRNA.

2 phases:

Transcription: Info in DNA, transfered to a molecule of mRNA. Leave nucleous, goes to cytoplasm (with the info). It takes place in the nucleous.

Translation: Once in the cytoplasm, mRNA joins the ribosome, translate info a protein. Diff protein, for each gene.

Replication/mutations:

• DNA can make copies of itself through replication.
• It allows a cell to divide and produce two identical daughter cells.
• During replication, mutations or alterations in the DNA sequence can occur.
• Mutations are responsible for introducing new characteristics in organisms.
• these mutations can lead to the evolution of species.

Chromosomes and the Cell Cycle:

• The cell cycle is the period from cell formation to cell division.
• The cell cycle consists of interphase (growth period) and mitotic divisions.
• Interphase is the non-dividing period and includes G1, S, and G2 phases.
• G1 phase: Cell grows in size, duplicates organelles, and performs functions.
• S phase: Chromosomes duplicate.
• G2 phase: Cell prepares for mitosis.
• Mitosis divides the nucleus and its chromosomes.
• Cytokinesis divides the cytoplasm, producing two daughter cells.

Mitosis:

• Phase of cell division in eukaryotic cells, it consists of the division of the nucleus.
• Mitosis is followed by cytokinesis, which is the division of the cytoplasm.
• Responsible for cell reproduction and regeneration in multicellular organisms.
• In unicellular organisms, mitosis can be considered as a form of asexual reproduction.
• Mitosis does not generate genetic variability, as daughter cells are identical to the mother cell.
• Somatic cells, such as epithelial cells and liver cells, undergo mitosis for growth and repair.

Interphase-Prophase-Metaphase-Anaphase-Telophase-Cytokinesis

Gregor Mendel:

• Austrian monk in the 19th century who studied pea plants.
• Discovered principles of heredity and heritable factors.
• Gene and chromosome concepts developed later.
• Chromosome theory of inheritance proposed by Sutton and Boveri.
• Genes confirmed to be DNA fragments by Watson and Crick.

Gene:

• Sequence of nucleotides (DNA or RNA) that carries trait information.
• Occupies specific position on chromosomes called locus.
• Passed from parents to offspring during sexual reproduction.
• Humans have 23 pairs (46) of chromosomes in most cells.

Homologous chromosomes:

• Pair of chromosomes with same structural features.
• Carry same genes in same loci, but may have different alleles.

Allele:

• Alternative form of a gene due to mutations.
• Found in same locus on homologous chromosomes.
• Determine same trait, but may have different versions.

Homozygous and heterozygous:

• Homozygous: Two identical alleles for a trait (e.g., AA or aa).
• Heterozygous: Two different alleles for a trait (e.g., Aa).

Dominance:

• Complete dominance: Dominant allele fully expressed, recessive has no effect.
• Codominance: Both alleles manifested in phenotype.
• Incomplete dominance: Intermediate phenotype observed.

Genotype and phenotype:

• Genotype: Genetic information specified by alleles (e.g., AaBb).
• Phenotype: Observable characteristics resulting from genes and environment. (e.g. blue eyes)