genetics obj. Flashcards
explain how cell division is important for growth, repair, and reproduction of all organisms
the cells in your body divide to grow longer bones and muscles, when you cut yourself or break a bone, cell division creates new cells to help repair the wound for healing. the cell theory states that all cells must come from other cells so the offspring of any organism must be formed with a pre-existing cell, sop cell division helps in reproduction of organisms
explain/describe the three main phases in cell cycle
Interphase: longest phase of the cell cycle, cell performs normal functions, and prepares for mitosis. chromosomes are duplicated then condensed.
Mitosis: two new nuclei are formed.
Cytokinesis: cell membrane pinches in to divide nuclei cytoplasm and organelles to form two daughter cells.
explain the four main stages in mitosis
prophase: chromosomes condense and shorten, nuclear envelope begins to disappear, mitotic spindle forms.
metaphase: chromosomes line up in the middle of the cell on the mitotic spindle, the membrane around the nucleus membrane dissolves.
anaphase: chromosomes separate and move to opposite ends of the cell along the spindle fibres.
telophase: mitotic spindle disappears, separated chromosomes arrive at opposite sides of the cell, nuclear envelope forms around each set of chromosomes, chromosomes begin to lengthen and become less condensed.
what is cancer and how and why does it occur
It is a disease whereby uncontrolled cell division creates a clump of cells known as a tumour. It is caused by errors in replicating cells DNA, or the organism is exposed to carcinogens.
describe the differences in asexual and sexual reproduction
Asexual reproduction involves only one parent. Sexual reproduction usually involves two parents, exceptions are the sponges, aphids, and grass sunflowers and roses.. Asexual reproduction produces offspring that are genetically identical to the parent, they are clones. The offspring from sexual reproduction has a mix of traits from both parents. Asexual reproduction can produce many offspring efficiently and quickly.
