Chapter 3 Flashcards
Basic chromosomes structure
- Chromatin (unwound DNA)
- DNA
- Chromosomes
👉🏻we have 46 double stranded chromos
Centromere
Connects two chromatids
Kintochore
Fibers
Telomere
Tips
Chromatids
Two single strands
How long does it take the cell cycle
24 hrs
G1 (Gap 1)
Cell grows, normal metabolic processes take place
S
Replication
G2 (gap 2)
Cell prepares for mitosis
Mitosis
Separation of the chromosomes (karyokinesis)
Cytokinesis
Cytoplasm seperates
Order of the cell cycle
- Interphase
- Prophase
- Metaphase
- Anaphase
- Telophase
Interphase
- DNA replication
- Chromatin
- Cell growth
- Nucleus represent
Prophase
- Nucleus disappears
- Nuclear membrane disappears
- Double stranded chromosome
- Centrioles migrate to poles
- Asters and spindles form
Metaphase
- Double stranded chromosomes line up at the equator
Anaphase
- Single stranded chromosomes move to poles
- Cell plate formation (plant) furrowing in animal cells
- Centromeres split
Telophase
- Two brand new daughter cells
- Nucleus reappears
- Astros and spindles disappear
- Cytokinesis ( plant produce a cell plate)
Does a zygote undergo mitosis or meiosis
Mitosis
Reasons why cells divide instead of grow
- The larger a cell becomes, the more demands the cell places on its DNA
- A larger cell is less efficient in moving nutrients and waste materials across the cell membrane
Cell size limitations
- Surface area to volume ratio
a) key factor in cell size
b) cell stays small
Diffusion limits cell size
- Movement from higher concentration to lower concentration
- Larger the distance, slower the diffusion rate
- A cell 20cm would require months for nutrients to get to the center
DNA limits cell size
- Larger cells need more DNA
- Needs more of everything
👉🏻most cells just have one nucleus
What does the DNA check to assure the cell divides properly
The DNA is checked to make sure it has replicated properly
Cyclins
Proteins that regulate the timing of the cell cycle
Internal regulatory proteins
All the cell cycle to proceed after certain events have occurs
External regulatory proteins
Growth factors stimulate the cell cycle. some cause it to slow down or stop
Why division?
- Growth
a) stem cells - Repair
- Reproduction
a) Asexual (genetically identical)
b) sexual
Apoptosis
A cell may die by accident due to damage or injury, or a cell may actually be programmed to die
Benign
Not cancerous
Malignant
Cancerous
What do malignant cells do
- Kills healthy tissue
- Block blood vessels
- Prevent organs from working properly
- Divide uncontrollably
Mutations caused by…
- Radiation
- Smoking/drugs
- Pollutants
- Chemicals
- Viruses
- Defective genes
Division in cancer cells
Cancer cells will continue to divide with mutations
Cancer- Mitosis out of control!
- Cells lose their ability to control growth
- Don’t respond to signals that regulate growth
- Divide uncontrollably
Dif in dividing in normal cells and cancer cells
When normal cells feel something is wrong they can blow themselves up, while cancer cells continue to divide
Metastasis
Cancer moves
Telomeres in cancer cells
They stay long
Chemical signals in cancer cells
Cancer cells ignore the chemical signals that start and stop the cell cycle
Radiation
Interferes with the copying of DNA
Chemotherapy
The use of chemicals to kill cancer cells that are weaker
Removal
Cancerous tumors
Tumor suppressor genes
Limit cell growth
Oncogenes
Promoting the growth of cells
How does BRCA function normally in cells
Help ensure the stability of the cells genetic material and help prevent uncontrolled cell growth
Do mutated BRCA genes indicate you will have cancer
No they just increase the risk
