Genetic Mutations

Genetic Mutation

• A genetic mutation is an alteration in the nucleic acid sequence.

Point Mutation

• A point mutation happens when a single nucleotide base is changed.

Silent Mutation

• A silent mutation results in no change to the protein sequence.

Nonsense Mutation

• A nonsense mutation introduces a stop codon, preventing complete protein production.

Missense Mutation

• A missense mutation changes the amino acid sequence, potentially affecting protein type/function.

Frameshift Mutation

• A frameshift mutation involves the insertion or deletion of nucleotides in numbers not multiples of three.

Mutagen

• A mutagen is an environmental or chemical agent that causes mutations.

Sickle Cell Anemia

• Sickle cell anemia is caused by a point mutation where adenine (A) is substituted for thymine (T) in DNA.

Chromosomal Mutation

• A chromosomal mutation involves a large segment of DNA.

Deletion Mutation Disorder

• Cri du chat syndrome is a deletion mutation disorder caused by missing part of chromosome 5.

Nondisjunction

• Nondisjunction occurs during cell division when chromosomes fail to separate.

Down Syndrome (Trisomy 21)

• Down Syndrome occurs when a person is born with an extra chromosome 21.

Klinefelter Syndrome

• Klinefelter syndrome occurs when a male is born with an extra copy of the X chromosome.

Turner Syndrome

• Turner Syndrome occurs when a female is born with only one X chromosome.

Cell Cycle

• The cell cycle involves DNA replication and the division of a cell into two daughter cells.

Mitosis

• Mitosis is eukaryotic cell division that produces two new identical somatic cells, called daughter cells.

Somatic Cells

• Somatic cells are all the cells in the body, except sperm and egg cells (sex cells).

Diploid

• A diploid cell has two complete sets of chromosomes, found in all somatic cells and totals 46 chromosomes in humans.

Haploid

• A haploid cell has a single set of chromosomes, found in sperm and eggs, with 23 chromosomes in humans.

Interphase

• Interphase is the stage where the cell spends the majority of its time for growth.

G0 Phase

• G0 phase is the resting phase of the cell cycle, where a cell is neither dividing nor preparing to divide.

Gap 1 (G1)

• Gap 1 (G1) involves cell growth and normal functions, including mitochondria replication.

DNA Synthesis (S)

• During DNA synthesis (S), DNA is copied.

Gap 2 (G2)

• Gap 2 (G2) involves additional growth, where chromatids become replicated chromosomes.

Mitosis (M)

• Mitosis (M) includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis).

Stages of Mitosis

• Mitosis undergoes 4 stages: Prophase, Prometaphase, Metaphase, Anaphase, Telophase and Cytokinesis

Prophase

• During prophase, DNA supercoils and chromosomes become visible.

Sister Chromatids

• Sister chromatids are held together at the centromere.

Prometaphase

• During prometaphase, the nuclear membrane breaks down, centrosomes migrate to poles, and spindle fibers appear.

Centrosome

• A centrosome is an organelle involved in the organization of microtubules and separation of chromosomes and is only found in animal cells.

Centriole

• A centriole is a cylindrical organelle found within a centrosome.

Centromere

• A centromere is the region of a chromosome to which spindle fibers attach.

Metaphase

• During metaphase, chromosomes line up in the center (middle) of the cell.

Anaphase

• During anaphase, spindles attach to the centromeres and pull sister chromatids away from each other to opposite poles.

Telophase

• During telophase, nuclear membranes reform in daughter cells, chromosomes form tight clusters at the poles and begin to unwind, becoming less visible.

Cytokinesis

• Cytokinesis is the process where the cytoplasm divides into two daughter cells.

Daughter Cells

• Daughter cells are exact copies of the parent cell.

Binary Fission

• Binary fission is the asexual form of cell division in prokaryotic cells, a less complicated and much quicker process than mitosis.

Asexual Reproduction

• Asexual reproduction is any form of reproduction that does not involve the fusion of gametes, resulting in offspring genetically identical to the parent.

Steps of Binary Fission

• Steps of binary fission include:
  • Organism duplicates its genetic material (DNA).
  • Cell starts to elongate.
  • A septum is formed between the two sides.

Meiosis

• Meiosis is the process by which sex cells (gametes) are produced.

Gonads

• Gonads are organs where meiosis occurs, specifically testis or ovary.

Haploid

• A haploid cell contains half the number of chromosomes, resulting in 4 non-identical daughter cells in meiosis.

Sexual Reproduction

• Sexual reproduction involves the combination of genetic material from two different organisms to produce a genetically unique zygote.

Recombination

• Recombination occurs during prophase 1, where sections of chromosomes are exchanged.

Tetrad

• Tetrad is the structure formed when chromosomes join up during recombination.

Recombinant Chromosomes

• Recombinant chromosomes are the resulting chromosomes with a mix of genes from both parents.

Independent Assortment

• Independent assortment occurs during metaphase 1, where different genes separate independently of one another.

Meiosis 1

• Meiosis 1 is the first phase of meiosis consisting of prophase 1, metaphase 1, anaphase 1, and telophase 1 & cytokinesis

Prophase 1

• Prophase 1 is the stage where chromosomes condense and the nucleus breaks down.

Metaphase 1

• Metaphase 1 is the stage where paired chromosomes line up in the center of the cell and recombination occurs.

Anaphase 1

• Anaphase 1 is the stage where paired chromosomes separate.

Telophase 1 & Cytokinesis

• Telophase 1 & Cytokinesis is the stage where 2 daughter cells are formed.

Meiosis 2

• Meiosis 2 is the second phase of meiosis consisting of prophase 2, metaphase 2, anaphase 2, and telophase 2 & cytokinesis.

Prophase 2

• Prophase 2 is the stage where chromosomes condense and a new set of spindle fibers form.

Metaphase 2

• Metaphase 2 is the stage where centromeres align in the middle of both cells.

Anaphase 2

• Anaphase 2 is the stage where chromatids split at the centromere and migrate along the spindle fibers to opposite poles.

Telophase 2 & Cytokinesis

• Telophase 2 & Cytokinesis is the stage where 4 daughter cells are formed.

Outcome of Meiosis

• Final outcome of meiosis is 4 unique cells with half of the genetic material (haploid), specifically 23 chromosomes in each cell for humans.