Flashcards in Chapter 5.1 Deck (29):
What does cell replacement mean?
Your cells continue to divide as you grow
What happens to your body after puberty?
Your body growth slows down but your body will continue to replace cells that take on a lot of "wear and tear"
What is the life span of skin cells?
What is the life span of stomach lining cells?
What is the life span of red blood cells?
What is the life span of brain cells?
What are the 3 stages of the cell cycle?
Interphase, mitosis & cytokenesis
What is interphase?
The first and longest stage of the cell cycle. It is made up of 3 phases
What are the 3 phases of interphase?
Growth & preparation, DNA replication, continued growth and preparation
What happens in the first stage: growth and preparation?
The cell increases in size and makes necessary proteins and some organelles begin to duplicate
What happens in the second stage: DNA replication?
DNA unwinds and seperates. Each side becomes a new template on which a new side forms. The cell then temporarily has 2 sets of DNA.
The process is controlled by enzymes.
What happens in the third stage: continued growth and preparation?
The cell continues to grow and actively makes proteins for the new cell after division.
Chromatin contains the replicated DNA, which is copied into RNA for protein synthesis.
Organelles are also duplicated.
What is mitosis?
The second and shortest stage of the cell cycle.
It is the process in which contents of a cell's nucleus divides.
What are the results of mitosis?
It results in 2 daughter nuclei, each with the same number and kinds of chromosomes as the parent cell
What happens next to the DNA molecules that replicated during interphase?
As the nucleus prepares to divide, DNA molecules join together to form the sister chromatids of a chromosome
What does the centromere do?
Holds the 2 sister chromatids together in the middle
What are the 4 phases of mitosis?
Prophase, metaphase, anaphase & telophase
What happens in prophase?
The replicated chromosomes coil up into an x-shaped chromosomes. The nucleolus disappears and the nuclear membrane breaks down.
Spindle fibres stretch across the cell. Centrioles move apart. Spindle fibres complete forming and the chromosomes attach. The nuclear membrane disappears.
What happens in metaphase?
The tugging action of the spindle fibres pulls the x-shaped chromosomes into a single line across the middle or equator of the cell
What happens in anaphase?
The spindle fibres begin to contract and shorten. This action pulls the centromere apart, allowing the sister chromatids to move to opposite pole of the cell.
When they seperate, each sister chromatid is considered a chromosome.
What happens in telophase?
One complete set of chromosomes is now at each pole of the cell. The spindle fibres begin to disappear and a nuclear membrane forms around each set of chromosomes. A nucleolus appears and now there are 2 nuclei in one cell and it is ready to divide.
What is cytokenesis?
The final stage of the cell cycle. It seperates the 2 nuclei into 2 daughter cells
How does cytokenesis work in an animal cell?
The cell membrane pinches together to divide the cytoplasm and organelles
How does cytokenesis work in a plant cell?
A cell plate forms along the centre to divide the cells
What is the importance of checkpoints in the cell cycle?
To monitor and ensure that all the activities within the cell are functioning properly
State 3 reasons why cells may not divide.
1. not enough nutrients to support cell growth
2. DNA within the nucleus has not been replicated
3. DNA is damaged
What is cancer?
Disease that results from uncontrolled cell division
How do cancer cells divide?
They divide uncontrollably in multiple layers and eventually form a tumour.
Cancer cells have large, abnormal nuclei because cell division checkpoints no longer function.