Cell Cycle: Phases and Components

• The cell cycle is a series of events in a cell that leads to division and duplication.
• A parent cell is the original cell that divides.
• Daughter cells are the new cells that result from the division of a parent cell.
• DNA (Deoxyribonucleic Acid) carries genetic information in cells.
• Chromosomes are structures within the nucleus of a cell made upon DNA which carries genetic information.
• Sister chromatids are two identical copies of a chromosome, connected at the centromere, that separate during cell division.

G1 Phase (Growth Phase)

• The cell grows in size, producing proteins and organelles essential for the next stages.
• A checkpoint ensures the cell is large enough, has sufficient energy, and is ready to begin DNA replication.

S Phase (DNA Replication)

• The cell duplicates its DNA, creating two identical copies of each chromosome.
• A checkpoint verifies DNA replication is complete and checks for errors in the newly synthesized DNA.

G2 Phase (Quality Control)

• DNA replication and synthesis occurs during this stage.
• A checkpoint detects and repairs DNA damage, ensuring the cell is ready to proceed to mitosis.

Cell Phase (Cell Division)

• This is where the process of cell division occurs.
• During this stage the cell divides, creating two new, identical components.
• The two components of cell division are mitosis and cytokinesis.
• Mitosis is the process of making new body cells.
• Meiosis is the type of cell division that creates egg and sperm cells.

Mitosis

• This is a fundamental process for life, where the cell duplicates all of its contents
• The cell then splits to form two identical daughter cells.

1. Prophase (Setting the Stage)

• The repeated coiling of chromosomes results in a thicker, shorter structure.
• This results in two sister chromatids.

2. Metaphase (The Line Up)

• Chromosomes align at the equatorial plane.
• Each spindle fiber from both centrosomes connects to each chromosome through its kinetochore to centromeres.

3. Anaphase (The Separation)

• Spindle fibers begin to contract shorter.
• Contraction causes the separation of genetically identical sister chromatids.

4. Telophase (Reconstruction)

• Chromosomes are at the opposing poles of the spindle.
• Cytoplasmic division, called cytokinesis, occurs concurrently, splitting the cell into two.

Cytokinesis (The Final Divide)

• In this final step, the cytoplasm divides as the cell membrane pinches inwards, eventually separating the cell into two daughter cells.
• This causes the two daughter cells to become physically separated.

Meiosis

• A type of cell division reduces the chromosome number by half, creating genetically diverse daughter cells.
• This is essential for sexual reproduction, as it produces gametes with half the usual number of chromosomes.
• Nucleus will undergo two divisions: Meiosis I and Meiosis II.
• Each process follows similar stages as mitosis.

Prophase 1

• Chromosomes condense and pair up, and crossing over occurs.
• Crossing over leads to homologous chromosomes exchanging genetic material.

Metaphase 1

• Chromosome pairs align along the cell's equatorial plane.
• Spindle fibers attach to the centromeres of the homologous chromosomes.

Anaphase 1

• Homologous chromosomes are pulled to opposite poles by the spindle fibers.
• Sister chromatids remain together.

Telophase 1

• Chromosomes reach the poles and the cell undergoes cytokinesis.
• Two non-identical haploid cells are formed.

Cytokinesis

• The first cytokinesis occurs after the first division of meiosis, resulting in two haploid cells.
• Each cell has half the number of chromosomes as the parent cell.

Prophase 2

• Chromosomes condense again, and a new spindle forms in each haploid cell.

Metaphase 2

• Chromosomes align at the cell's equatorial plane in each haploid cell.

Anaphase 2

• Sister chromatids are finally separated and pulled to opposite poles.

Telophase 2

• Chromatids reach the poles, and the cells undergo cytokinesis.
• This results in four non-identical haploid daughter cells.

Cytokinesis

• The second cytokinesis follows the second division of meiosis.
• Sister chromatids separate, with four haploid daughter cells resulting, each including a single copy of each chromosome.

Mutation

• This is a change in the base sequence of DNA.
• Mutagens are factors that induce mutations.

Some Genetic Disorders

• Down’s syndrome is caused by an extra copy of chromosome 21 (trisomy 21).
• Decreased muscle tone and slanting eyes, and stockier builds are characteristics of this development.
• Can lead to moderate mental retardation.
• Trisomy is an extra copy of a chromosome.
• Edward’s syndrome, the second most common trisomy (trisomy 18), leads to mental and motor retardation.
• Other traits include congenital anomalies and clenched hands with overlapping fingers
• Cri du chat is caused by the deletion of part of the short arm of chromosome 5.
• It leads to high-pitched cries that sound like a cat, small head and jaw, and moderate to severe mental retardation.
• Klinefelter’s syndrome relates to sex chromosome aneuploidy XXY, leading to sterility.
• Can be sterile with longer arms and legs
• Often shy and quiet and have a higher incidence of speech delay.
• Turner syndrome relates to sex chromosome aneuploidy X.
• Can cause underdeveloped female sexual characteristics, often having short stature, with a low hairline.
• A “caved-in” appearance to the chest

Types of Mutations

• Mutations can occur in two different types of cells: reproductive and body cells.
• Only mutations in reproductive cells are heritable.

Gene Mutation

• Gene mutation is a permanent change in DNA sequence that makes up a gene.
• Changes in the DNA sequence may occur during replication.
• Substitution: at least one of the bases in the DNA strand is changed.
• Insertion: at least one base in the DNA strand is added.
• Deletion: at least one base in the DNA strand is deleted.

Chromosomal Mutation

• Occurs at the chromosome level during cell cycle and meiosis.
• Leads to deletion, duplication, or rearrangement.

  • a. Duplication - extra copies of genes are generated in a chromosome

    • Examples: Down’s Syndrome, Edward’s Syndrome, and Klinefelter’s Syndrome

  • b. Deletion - some of the genetic materials break off from the chromosome

    • Examples: Cri du chat and Turner syndrome

  • c. Inversion - a broken chromosome segment gets reversed and put back on the chromosome.

    • Examples: Hemophilia A Hunter Syndrome

  • d. Translocation - a fragment breaks off one chromosome and attaches to another.

    • Examples: Chronic Myeloid Leukemia (CML) and Burkitt’s Lymphoma

Human Karyotyping

• Karyotyping is a medical procedure using an image of the full set of chromosomes of an individual.
• It displays number, size and shape.
• Can be done through examination of cells from or sampling of placental membranes.

Traits

• A trait is a characteristic of an organism
• "flower color" is a gene, with genes being a part of a chromosome that helps determine a specific trait.
• An allele is a form of a gene.
• An allele is the "blue" form, one form of the gene is the "red" form of the gene.

Chromosomes

• Chromosomes come in pairs, one being inherited from one parent and the other from the other parent.
• The pair of chromosomes is called a homologous pair, and they have the same genes on them.
• Humans have 23 chromosome pairs and approximately 40,000 genes.
• A pea flower has 7 chromosome pairs.
• A fruit fly has 4 chromosome pairs.
• A potato has 24 pairs.
• A horse has 32 pairs.

Dominant and recessive alleles

• Only one red allele is needed for the flower to look red.
• Scientists call this a dominant allele
• Two blue alleles are needed for the flower to look blue, where scientists call this a recessive allele.

Alleles

• The traditional symbols used for alleles are big and small letters, to denote which is dominant
• If "R" is used for Red allele, using "r" would relate to denote blue.
• Phenotype- the observed trait of an organism.
• Genotype trait– the two alleles that an organism has for a trait.
• Genotype is either, RR, Rr, or rr.
• Homozygous– the two alleles are the same, for example if the genotype is RR they are Homozygous.
• Heterozygous– the two alleles are different, for example if the genotype is Rr they are Heterozygous.
• Punnett Squares predict ratios of all genotypes and phenotypes produced

Biotechnology

• Manipulation of living organisms or parts of organisms to make products useful to humans.
• Used to produce new characteristics in plants and animals, is is a technology that manipulates nature for the benefit of mankind.
• Traditional Biotechnology refers to the practice of using living organisms to make new products or modify existing ones, similar to practices used from the 8000 B.C.E. up to the middle of the 20th century.

Ancient Biotechnology (prior to 1750)

• Focuses on domestication and agriculture where plants is used for food, while other used to selectively bred for desired characteristics. Some animals used for food and to do work. Modern Biotechnology (1950’s to present)
• Includes deliberate manipulation of genes, cells, and living tissues in a predictable and controlled manner to generate variations in the genetic make-up of an organism or produce new tissue.
• This includes all the processes and techniques from the 1950’s up to the present.

Current Uses of Biotechnology

• Plants are cloned using various techniques of asexual propagation as well as the modification of plants by inserting or moving DNA.
• Termed through transgenic, biotech, GM (genetically modified), or GE ( genetically engineered)
• Animals are cloned.
• Medicine process of biomanufacturing can genetically produce cells of whole plants and animals as well as engineering pharmaceuticals (pharming).
• Includes personalized medicine relating to genomics and gene therapy.
• Use of organisms to remedy on environmental problem referred to as bioremediation.

Branches of Biotechnolgy

• Blue covers Marine and aquatic applications
• Green covers Agriculture applications
• Red covers Medical applications
• White covers Industrial applications.

Adaptations to Land

• Root systems which includes Shoot systems and Vascular tissues are adapatations to land in life sustained by plants.

Methanogens

• Are microorganisms that produce methane byproducts from metabolism. Therm refered to as a "Thermophile". This type of extremophile lives and or thrives at relatively high temperatures, between 41 and 122 °C, most of these are archaea.

Halophiles

• Are extremophiles and thrive in high salt concentrations.

Father of Taxonomy

• Carolus Linnaeus' system in the 1700's of Hierarchical taxonomic classification has classifications of levels

Taxonomy

• Is a branch of science that deals with classifying organisms –to construct internationally shared classification system to study traits and genes

Animals

• Animals multicellular organisms that dont have cell walls but do have:
  • Invertebrate– these do not have a backbones
  • Vertebrate– these do have a vertebral column, vertebra that classify as
    • SPONGE : these Simplest animals do not have digestive systems but do have Pores that have entry of water and food and do have a Osculum that removes waste material
    • CNIDARIANS: these animals have tentacles with stinging cells (nematocyst) that has Defense and capturing prey and also include Jelly fish and corals:
    • FLATWORMS: these have Free-living (planaria) and or Parasitic (tapeworm) properties that also lack a digestive system making then Transmitted to human through eating uncooked meat, fish, and or pork

ROUNDWORMS

• These are Free-living (decomposers) and are Parasitic (ascaris and pinworms) in diganosis.

SEGMENTED WORMS

• Earthworms are annelida that swallofood as they burrow creating waste material (casting: these also Breathe through skin through the process of Leeches with both Blood sucking (both ends. that is also used with anti-clotting chemical during Medicine.

REPTILES

    Have smooth/rough scales for protection, Lay eggs with shell, snakes and lizards and can be alligators and crocodile.