Biomed final review 5
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How do cells renew themselves?
through cell division
True or false: all cells make copies of themselves in a growing embryo
What types of cells are constanly regenerating through cell division?
- Bone marrow
- Red and white blood cell
- and intestinal lining
What cells cannot divide after birth ?
- Heart muscle
What are the steps of the Cell cycle?
- Mitosis (actual, active cell division)
- -G1 ("growth-1" or "gap-1")-
- -G0 (quiescence)
- -S (replication of DNA)
- -G2 ("growth-2" or "gap-2")
G1 phase (first growth phase)
- After mitosis, a dividing cell enters this stage
- G1 takes 8-10 hours to completeif the cell is activelyt dividing, it prepares for the next division
- Cell duplicates organelles and cytoplasmic components
- In order to enter S phase, cell in must pass a checkpiont
- If a cell cannot pass the G1/S checkpoint, or if cell is quiescent (not actively dividing), cell remains in G0
- For example brain cells (neurons) spend a lifetime in G0
- Cells that take longe than the totalof 24 hours to pas through the cycle also wait in G0
- A liver cell divides onces every seven years spending all that time in G0 before passing onto S phase.
S phase (synthesis)
- DNA is replicated (copied)
- All DNA must be duplicated in preparation for cell division
- this proccess takes about 8 hours
- The cell finalizes its preparations for mitosis
- Cell now carries dougle the amount of normal DNA
- -in G1 had 46 DNA molecules, now has 92
- Duplication of centromeres
- Second checkpoint (G2/M) must be crossed
- -no normal cells are locked in G2
- After 4-6 hours cell enter mitosis
What is Mitosis?
- Mitosis is the actual active division of the cellInterphase is not a true phaseof mitosis, but all other parts of cell cycle
- -G1, G0, S, G2 are interphase
- mitosis has 4 stages
What is the difference between Mitosis and Cytokinesis?
- Mitosis is the process of nuclear division
- genetic material must be parcelled equally between cells
- chromosomes form, get pulled apart, dissolve
- Cytokinesis is the process of cell division
- plasma membrane between cells tightens like a rubber band and pinches of two cells where there was one before
- this separates the genetic material, cytoplasm and organelles into two equal daughter cells
- a segment of DNA that codes for a protien
- a region of DNA tha is made into protein
- Messenger RNA (mRNA) carries the code for a primary sequence of amino acids in protein
Module 5 obj. 4
- messenger RNA
- Nuclear pores
Graphic objective 6. Explain the process by which pre-mRNA is edited to a messenger RNA.p.241
Graphic objective 8. Explain how mRNA is translated into protein
Graphic Objective 10. Define: codon, anticodon. Summarize the steps in mRNA translation to form protein.
Graphic Objective 21. Define dominant and recessive genes. Explain sickle cell anemia and albinism in terms of Mendelian genetics. Construct and analyze Punnet squares for analysis of dominant and recessive gen inheritance.
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