5x objective- 10 X 5 = 50x 10x objective- 10 X 10 = 100x 50x objective- 10 X 50 = 500x Flashcards
What are the 3 major reasons cells need to make copies of themselves?
replace damaged cells, growth, asexual reproduction
What is the longest part of the cell cycle?
Interphase
What 3 phases make up interphase?
G1, S, G2
Describe what happens during each of the phases of interphase.
G1-active growth and protein synthesis
S-DNA replication
G2- cell organelles are produced to prepare for division
What is the division of the nucleus called?
mitosis
What is the division of the cytoplasm (and the rest of cell contents) called?
cytokinesis
When a cell divides what are the 2 new cells called?
daughter cells
Prophase
Nucleus disappears
spindle fibers form
DNA condenses into chromosomes (sister chromatids)
Metaphase
Chromosomes align along the MIDDLE of the cell
spindle fibers attach to chromosomes at the centromere
Anaphase
Chromosomes separate at the centromere and move AWAY
chromatids are pulled towards opposite ends of the cell by spindle fibers
Telophase
Chromosomes unwind into thin strands of DNA (chromatin)
spindle fibers disappear
nuclear membrane reappears as TWO nuclei are formed.
A human has ___ total chromosomes.
46
__ of those chromosomes are from the mother, __ are from the father.
23, 23
Define diploid.
Cells that have two sets of chromosomes (46 in humans)
Define haploid.
Cells that have one set of chromosomes (23 in humans)
Skin cell
diploid
Sperm cell
haploid
Muscle cell
diploid
Brain cell
diploid
Blood cell
diploid
Egg cell
haploid
Sex cells are also referred to as ….
gametes
Why is having sex cells which are haploid so important? (THINK - this is not explicitly in your notes)
Because they have to combine with another gamete to create a new offspring.
46 → 23 + 23 → 46
Sperm cell (23) + Egg Cell (23) = Zygote (46) (zygote = new human cell)
What important event occurs during prophase I? Explain what this process does.
Crossing over occurs where the chromatids in the tetrad exchange information. This causes new combination of alleles (genetic shuffling).
Mitosis
replacement, growth, repair creates somatic (body) cells
1 division
2 daughter cells
Diploid cells
Identical to parent
Identical to sister cell
Both mitosis and miosis
DNA replication during interphase
makes new cells
starts with 1 cell
Meiosis
reproduction
creates gametes
2 divisions
4 daughter cells
haploid cells
different from parent
different from sister cells