Unit 9 - Reproduction: Mitosis, meiosis, sexual & asexual reproduction, flower reproduction (7th Grade Science)

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cell cycle
the life cycle of a cell
chromosome
in a eukaryotic cell, one of the structures in the nucleus that are made up of DNA and protein; in a prokaryotic cell, the main ring of DNA
homologous chromosomes
chromosomes that have the same sequence of genes and the same structure
mitosis
in eukaryotic cells, a process of cell division that forms two new nuclei, each of which has the same number of chromosomes
interphase
occurs before mitosis begins when chromosomes are copied
prophase
the first phase of mitosis when chromosomes condense from long strands into rod-like structures and the nuclear membrane ruptures
metaphase
the second phase of mitosis during which the nuclear membrane is dissolved and paired chromotids align at the cell's equator (middle)
anaphase
the third phase of mitosis during which the chromotids separate and move to opposite sides of the cell
telophase
the fourth phase of mitosis during which mitosis is completed when a nuclear membrane forms around each set of chromosomes, and the chromosomes unwind
cytokinesis
occurs after mitosis when cells without a cell wall pinches in two or when cells with a cell wall form a plate between the two new cells
DNA
deoxyribonucleic acid; the hereditary material that controls all cell activities, including the making of new cells
binary fission
a form of asexual reproduction in which one prokaryotic cell such as bacteria divides to form two identical cells.
meiosis
the process by which sex cells (egg or sperm) reproduce; the number of chromosomes decreases to half the original number by two divisions of the nucleus to produce more sex cells
asexual reproduction
the way most single-celled organisms and some plants and animals reproduce; only one parent organism is needed
sexual reproduction
the way most multi-celled organism reproduce; two parent sex cells join together to form offspring that are different from both parents
prophase I (meiosis)
the step of sex cell reproduction during which each chromosome makes an exact copy of itself forming two halves called chromatids, the chromosomes thicken and shorten, and the nuclear membrane disappears, and similar (homologous) chromosomes pair up with one another, and exchanging of genetic information (crossing over) occurs
metaphase I (meiosis)
the stage of sex cell reproduction during which homologous chromosome line up at the equator (middle) of the cell
anaphase I (meiosis)
the step of sex cell reproduction during which the chromosomes separate from their homologous partners and then move to opposite ends of the cell (away from the center)
telophase I (meiosis)
the step of sex cell reproduction during which the nuclear membrane reforms, and the cell divides, but the paired chromatids are still joined
cytokinesis I
the step of sex cell reproduction in which two completely separate cells now exist from the one original cell with each of these two cells containing one member of each homologous chromosome pair. Note that the chromosomes are not copied again before the next step in this process
prophase II (meiosis)
the stage in sex cell reproduction during which new spindle fibers form and attach to the centromeres
metaphase II (meiosis)
the step of sex cell reproduction during which the chromosomes of the two cells line up at the equator (center) of each cell
anaphase II (meiosis)
the step of sex cell reproduction during which the chromatids in each of the two cells pull apart, and move to opposite ends of the cell
telephase II (meiosis)
the stage of sex cell reproduction during which the nuclear membrane forms around the separated chromosomes, and each of the two cells begins to divide.
cytokinesis II
the final result of sex cell reproduction which has formed four new cells from the original single cell with each of these new cells containing half the number of chromosomes present in the original cell
budding
a type of asexual reproduction in which part of a parent organism pinches off and forms a new organism
fragmentation
a type of asexual reproduction in which parts of an organism breaks off and then develop into a new individual that is identical to the original
regeneration
a type of asexual reproduction, similar to fragmentation in which a body part that the organism has lost develops into an entirely new organism
egg
a sex cell produced by female
sperm
the male sex cell
stigma
the part of the pistil of a flower that receives pollen into which pollen tubes begin to grow through the style towards an ovule
ovule
the plant part that contains the embryo sac and the female germ cell, which after fertilization develops into a seed.
ovary
the enlarged lower part of the pistil in a flower enclosing the ovules or young seeds.
pollination
when pollen is moved from anthers to stigmas in during the beginning of the reproduction cycle in flowers
fertilization
when the sperm fuses with the egg inside the ovule during the reproductive cycle in plants
plantlets
a type of asexual reproduction in which tiny plants grow along the edge of a plant's leaves, fall off, and grow in to new plants on their own
tubers
a type of asexual reproduction in which underground stems produce new plants after a dormant season
runners
a type of asexual reproduction in which new plants grow horizontally from above-ground stems
cutting
a type of asexual reproduction in which part of a plant is cut and planted and grows into a separate plant identical to the one from which it was cut
centriole
the organelle that organizes the spindle fibers to separate chromosomes during animal cell mitosis
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