Many genes coding for one phenotype. Each copy of the allele (found at loci on the chromosome) has a small effect on the characteristics. The effects of several alleles together contribute to the phenotype of an individual. TANNING • Melanin is made in melanocytes in...
• The epigenome influences which genes can be transcribed in a particular cell. • The attachment of X to the DNA of a gene prevents transcription to mRNA, by stopping the RNA polymerase binding. • The modification by addition of X affects how tightly the DNA is...
• Cell organelles - mitochondria, ribosomes, nucleus • Cells - white blood cell, villi, sperm, goblet • Tissues - Cardiac, muscle, epithelial, nervous, connective • Organs - liver, heat, kidney • Organ systems - respiratory, cardiovascular • Organisms...
Gametes are formed from cells in the reproductive organs by a type of cell division called meiosis. The cells that are formed by meiosis have half the number of chromosomes as a body cell (they are haploid). The main features of meiosis are: - • The cell divides...
Totipotent: can mature into any type of body cell in an organism, including the cells that make up the placenta Pluripotent: can mature into any cell in the body, but not the placenta Multipotent: can mature into a few different types of cell Unipotent: only can...
Ribosome is attached to the rough endoplasmic reticulum. It's made up of proteins and RNA, and not surrounded by a membrane. Golgi apparatus is a group of fluid-filled, membrane-bound flattened sacs, vesicles are often seen at the edges of the sacs. • Transcription of...
MAGNIFICATION EQUATION Magnification = image length / actual length LIGHT MICROSCOPY AKA Optical Microscopes use light and several lenses to magnify a sample. Light from the Condenser Lens, and then through the Specimen where certain wavelengths are filtered to...
Sperm have special features that make them well adapted: flagella/streamline, acrosome, haploid nucleus and mitochondria for energy. The egg is large and unable to move independently. The cytoplasm contains protein and lipid food reserves. • Sperm reaches the ovum •...
Crossing over is when two sister chromatids join up together at the chiasma. At the chiasma, the chromatids break and exchange section of genetic material. [Prophase (I)] Independent assortment; the chromosomes line up along the equator in their homologous pairs. The...
Cells divide on a regular basis to bring about growth and asexual reproduction. The cells divide in a sequence known as the cell cycle. There is a period of non-division known as interphase, when cells increase in size, mass and carry out normal cellular activities...
Pollen grain lands on the stigma and pollen tube grows through the style. • Haploid generative nucleus divides to form two haploid gametes nuclei that move down the pollen tube. • Tube grows through embryo sac inside the ovule and the two male gamete nuclei enter the...
EUKARYOTIC CELLS • Cell-surface (plasma) membrane • Nucleus • Mitochondria • Chloroplasts (plants) • Golgi apparatus • Golgi vesicle • Lysosome • Ribosome • Rough endoplasmic reticulum • Smooth endoplasmic reticulum • Cell wall (plants) • Cell vacuole • Centrioles...