unit 7 Flashcards
cell cycle and cell divison
why do cells divide?
reproduction, growth, repair, and to stay small so that there is more surface area to volume ratio (SA:V) for nutrients to reach the nucleus through diffusion
true or false: during the cell cycle, a cell grows, prepares for cell division, and divides to form 2 somatic (body) daughter cells that are diploid (2n) (contains both sets of chromosomes; a set of mom’s chromosomes AND a set of dad’s chromosomes).
true
examples of human somatic cells?
skin cells, heart cells, bone cells, muscle cells, blood cells, nerve cells, etc.
examples of plant somatic cells?
leaf cells, flower cells, tulip cells, rose cells, etc.
true or false: each new cell will start the cycle once
false, each new cell will start the cycle all over again
chromatin–
unfolded/uncoiled DNA (stretched out)
chromosome–
folded/coiled DNA, the fold/coils are held together by proteins called histones
the cell cycle has 2 main stages, what are they called?
interphase (chromatin is visible) and cell division (chromosome is visible)
what is the longest phase of the cell cycle?
interphase
interphase–
cells grow and carry out their regular functions, chromosomes are copied (duplicated/replicated), cell prepares for division (duplicates all the organelles)
G1–
growth 1: make proteins and organelles
S phase–
synthesis, DNA is copied/replicated
G2–
growth 2: make molecules needed for division
homologous chromosome–
chromosomes from mom and dad that are the same size and contain the same gene (type of information, hair color, eye color, hair texture, etc.) at the same place on the chromosome (however, the chromosomes may have different versions of the genes)
true or false: the duplicated chromosomes are attached to each other at the centromere, and are called sister chromatids
true
how many total chromosomes does a human have?
46 chromosomes in 23 pairs
what is the order of mitosis?
prophase, metaphase, anaphase, and telophase
prophase (mitosis)–
DNA (chromatin) condenses (coils together) and the chromosomes become visible, nuclear membrane disappears, centrioles separate
metaphase (mitosis)–
chromosomes line up in the middle of the cell’s (equator), chromosomes connect to the spindle fibers that were made by the centrioles
anaphase (mitosis)–
centromeres divide and spindle fibers begin to shorten, sister chromatids separate and move to opposite poles (apart)
telophase (mitosis)–
chromosomes reach the opposite ends (poles) of the cell, nuclear membrane forms again, cell begins to split in half
cytokinesis–
cytoplasm splits in half forming 2 identical daughter cells, in animal cells the cell membrane pinches inward creating a cleavage furrow, and in plant cells, a cell plate forms between the 2 daughter cells.
how many daughter cells does mitosis produces?
mitosis produces two identical somatic (body) daughter cells
true or false: the somatic daughter cells are diploid (contains both sets of chromosomes; a set of mom’s chromosomes and a set of dad’s chromosomes)
true
what is cancer caused by?
cancer is caused by abnormal cell cycle, abnormal cell cycle produces mass of cells called tumor, cancer occurs only in multicellular organism like plants, animals, and fungi
meiosis–
the process of nuclear division where the number of the chromosomes is halved
how many daughter cells are produced in meiosis?
four
all daughter cells haploid or diploid in meiosis?
haploid
what does meiosis make?
gametes (sperm and egg)
independent assortment–
during meiosis, the chromosomes move randomly to separate poles, this means each gamete will have 1 or many different possible combinations of chromosomes
crossing over (meiosis)–
chromosomes exchange sections by swapping genetic material between a pair of homologous chromosomes, the chromatids next to each other “cross over”
true or false: crossing-over in meiosis decreases variability/diversity
false, crossing over in meiosis increases variability/dirversity
true or false: crossing-over in meiosis increases the already huge number of different possible gamete types produced by independent assortment
true
spermatogenesis–
production of male gametes (sperm)
where does spermatogenesis occur?
occurs in the testes (germ cells), two divisions produce four sperm cells
how much sperm does men produce each day?
men produce about 250,000,000 sperm per day
oogenesis–
production of female gametes (eggs)
where does oogenesis occur?
occurs in the ovaries (germ cells), two divisions produce three polar bodies that die and one egg
why do polar bodies die?
because of unequal division of the cytoplasm, and starting at puberty, one egg matures every 28 days
1 sperm + 1 egg =
1 zygote
true or false: cell division of body cells (somatic) is called mitosis
true
true or false: cell division that produces gametes is called meiosis
true
how many diploid cells does mitosis produces?
2 diploid cells (2n)
how many haploid cells does meiosis produces?
4 haploid cells (n)
how many cell division does mitosis have?
one cell division
how many cell division does meiosis have?
two cell divisions
true or false: in mitosis, all cells are identical
true
true or false: in meiosis, all cells are different
true
