Biology Notes: Cells, Reproduction & More
Biology Notes
Different Parts of Flowers
Stamen (male)
| Pistil (female)
|
| Ovary contains Ovules, which develop into seeds upon fertilization |
How Twins Are Formed
Fraternal TwinsFraternal twins are formed from the fertilization of two eggs by two different sperm. They are also known as ‘dizygotic twins’, or ‘non-identical twins’. | Identical TwinsIdentical twins are formed from the splitting of one embryo. They are also known as ‘monozygotic twins’. |
Different Types of Cells and Cell Parts
Animal Cells
| Both
| Plant Cells
|
Cell Parts
- Nucleus: Regulates all cell activities
- Cell Membrane: Is made out of phospholipids and proteins
- Mitochondrion: Site of cellular respiration “power house”
- Lysosome: Suicide Sacks that contain digestive enzymes
- Rough Endoplasmic Reticulum: Contains Ribosomes, transports proteins and other materials
- Smooth Endoplasmic Reticulum: Contains no ribosomes, stores proteins
- Nucleolus: Dark spot of chromatin in the nucleus where ribosomes are produced
- Cytoplasm: Colloid that contains water and nutrients and supports the organelles
- Organelles: The parts of a cell with a particular function
- Prokaryotic: Cells with no true nucleus and no membrane-bound organelles
- Eukaryotic: Cells that contain a true nucleus and membrane-bound organelles
- Centrioles: Only in animal cells, aid in cell division
- Ribosomes: Produce Proteins
- Chloroplast: Found only in plants, site of photosynthesis
- Vacuoles: Large storage sacks found mainly in plants
- Cell Wall: Structure in plants made of cellulose that is outside of the cell membrane
- Chromatin: Thin strands of DNA and proteins found in the nucleus of a cell.
- Cell: Smallest unit of life
- Cytoskeleton: Long protein filaments in the cytosol that support the cell.
Different Types Of Specialized Cells
- Neuron Cells: Neurons are specialized cells that carry messages within the human brain.
- Muscle Cells: Muscle cells make movement possible. These cylindrical cells are made up of banded fibres that allow for contraction.
- Sperm Cells: Specialized sperm cells are necessary for human reproduction. These cells are made up predominantly of a nucleus.
- Red Blood Cells: Red blood cells carry oxygen around the body, delivering it to organs that require this life-giving gas.
- Leukocyte: Leukocyte cells work to keep the human body free of infection. These cells find and destroy microbes within the human body, responding to and treating infection.
Sexual and Asexual Reproduction
Sexual ReproductionSexual reproduction is a biological process that creates a new organism by combining the genetic material of two organisms in a process that starts with meiosis, a specialized type of cell division. Each of two parent organisms contributes half of the offspring’s genetic makeup by creating haploid gametes. Most organisms form two different types of gametes. In these anisogamous species, the two sexes are referred to as male (producing sperm or microspores) and female (producing ova or megaspores). | Asexual ReproductionAsexual reproduction is a process by which organisms create genetically similar or identical copies of themselves without the contribution of genetic material from another organism. Bacteria divide asexually via binary fission; viruses take control of host cells to produce more viruses; Hydras (invertebrates of the order Hydroidea) and yeasts are able to reproduce by budding. These organisms often do not possess different sexes, and they are capable of “splitting” themselves into two or more copies of themselves. Most plants have the ability to reproduce asexually and the ant species Mycocepurus smithii is thought to reproduce entirely by asexual means. |