10.1- Cell Growth and Reproduction
True or False: Mitosis is a form of sexual reproduction.
False- Asexual reproduction
The special proteins responsible for initiating changes in a cell are called
Cyclins
True or False: All cells found in an adult human are unipotent.
False- some cells are multipotent (i.e stem cells)
The longest phase of mitosis is...
Prophase
True or False: Cell division is an uncontrolled process of growth, replication and division.
False - controlled
Describe what a multipotent cell is.
Multipotent cells are groups of cells that are not specialized and differentiate when they renew and replace cells in their adult body, like skin and blood cells. These are also known as adult stem cells.
The phase where all cell growth and DNA replication occurs is called...
Interphase
Describe internal regulatory proteins.
Proteins that control the rate of processes inside of the cell. They make sure the cell cycle is a controlled, step-by-step process. For example: proteins will ensure that spindle fibers have attached to the centromeres of the chromosomes before the cell moves into anaphase.
What is a blastocyst?
After about four days of development, a human embryo forms into a blastocyst, a hollow ball of cells with a cluster of cells inside known as the inner cell mass and is considered pluripotent. The outer cells form tissue that will attach the embryo to its mother, while the inner cells will become the embryo itself.
Which type of reproduction, sexual or asexual, is best suited for organisms that live in a place where environmental conditions are unstable and changing? Why?
Sexual reproduction since genetic diversity gives the species an advantage by being better suited to adapt to a new environment or if the environment changes.
Describe the three phases of interphase.
G1 - Where the cell grows and matures. The cell goes through its normal functions. S Phase - DNA is synthesiszed or replicated. After this phase, there are a total of 92 chromosomes as the original chromosomes have been copied. G2 - The cell prepares for division. Cyclins will help ensure the cell is ready for mitosis.
Describe external regulatory proteins.
Proteins are affected by external events that occur outside of the cell (i.e injury, virus, or regular growth & development). They tell a cell when to start or stop dividing.
Describe what totipotent cells are. Why are they important? When are they found during development?
Totipotent cells are cells that have the potential to differentiate into all cells needed for the embryo to grow and develop - this has the potential to form all the specialized cells in the body, the placenta which will allow the embryo to grow and the umbilical cord that will connect mother to offspring. Only the fertilized egg and the cells produced by the first few cell divisions (usually within 4 days) of embryonic development are truly totipotent.
Explain why sexual reproduction can be beneficial to a species' survival but may not be beneficial to an individual organism.
Sexual reproduction is dangerous and risky for most organisms making it less likely that the organism may survive. However, organisms need to be able to adapt to changing environments in order for the species to survive. When offspring are born with slightly different genetics, the variety in mutations and adaptations increases, helping the species as a whole survive if the environment changes.
Describe the 4 phases of mitosis.
Prophase - The nuclear envelope begins to dissipate as the chromosome strands condense together. Centrioles move to either side of the cell, carrying newly formed spindle fibers. Metaphase - Spindle fibers attach to the chromosomes at their centromere (center of the duplicated chromosome) and force the chromosomes to line up in the center of the cell. Anaphase - Spindle fibers and centrioles will pull back, splitting and pulling back the chromosomes to either side of the cell. Telophase - The nuclear envelope forms around each set of 46 chromosomes. Spindle fibers dissipate and the cell membrane begins to show signs of being pinched.
Describe the difference between benign and malignant tumors.
Benign tumors are masses of cells that grow uncontrollably for a time but are harmless. Malignant tumors are considered cancerous and will invade and destroy surrounding tissue, absorbing all necessary nutrients, blocking nerve connections, and preventing organs from functioning properly.
Why are stem cells such an important part of medicine today?
Stem cells are a type of cell that can develop into many other different types of cell. Stem cells can also renew themselves by dividing, even after they have been inactive for a long time.Scientists believe this may offer potential treatments for conditions such as diabetes and heart disease. For instance, if someone has damaged tissue in their heart, it might be possible to stimulate the growth of healthy tissue by transplanting laboratory-grown stem cells into the patient's heart.