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Why do cells reproduce (divide)?
Demand on DNA, substances can't diffuse into cells with large volume as quickly as smaller cells.
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How Bacteria reproduce. DNA copies and then the cell splits in two.
Binary fission
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How to eukaryotic body cells reproduce?
Mitosis
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DNA that is loose and uncoiled when a cell is not dividing.
Chromatin
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DNA that is tightly coiled just before cell division
Chromosomes
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Each half of a copied chromosome (each half of the X)
Chromatid
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Point where sister chromatids attach.
Centromere
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How do you count the number of chromosomes in an organism?
Count centromeres
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If there are 6 chromosomes in a cell and the DNA has copied, how many chromatids are there?
12
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What are the phases of the cell cycle?
G1, S, G2, Mitosis, Cytokinesis
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The longest phase of the cell cycle. Includes G1, S, and G2.
Interphase
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A cell in this stage is no longer dividing.
Gap 0 (G0)
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Period of growth before division
Gap 1 (G1)
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DNA replicates during this stage of the cell cycle.
Synthesis (S)
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Second period of growth during the cell cycle.
Gap 2 (G2)
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Division of the nucleus.
Mitosis
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Divison of the cytoplasm
Cytokinesis
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Fibers that help move the chromosomes around by attaching at the centromeres.
Spindle Fibers
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Only in animal cells, the spindle fibers extend from these to attach to the chromosomes.
Centrioles
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What is the goal of mitosis?
To creat identical cells. Creates somatic cells.
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What are the phases of mitosis?
Prophase, Metaphase, Anaphase, Telophase
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Phase of mitosis in which nuclear envelope breaks down, centrioles separate and spindle fibers form. Chromosomes are visible.
Prophase
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Phase in mitosis in which chromosomes line up in the middle (at the equator).
Metaphase
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Phase in mitosis in which sister chromatids separate and are pulles to opposite poles (sides of the cell).
Anaphase
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Phase of mitosis in which chromosomes begin to become chromatin. 2 nuclear envelopes reform around chromosomes. Spindle fibers break down.
Telophase
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How is cytokinesis different in plants and animals?
In plants a cell plate forms beftween the two cells and the cell wall forms on either side of the plate. In animal cells a cleavage furrow forms and the cell divides.
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A mutation in the DNA that controls the cell cycle. The result are cells growing out of control.
Cancer.
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How is the cell cycle controlled?
There are checkpoints to make sure the steps of the cell cycle have properly occured.
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A tumor that does not spread or invade other parts of the body.
Benign tumor
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A tumor that invades surrounding tissues and can spread to other areas of the body.
Malignant tumor
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Cancer that has spread
Metastasis
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Body cels (hair, skin, and muscle cells)
Somatic cells
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Haploid sex cells (egg and sperm)
Gametes
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What is the goal of meiosis?
To creat sex cells with half the number of chromosomes.
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Chromosomes similar in size, shape and genetic information. One comes from mom and one comes from dad.
Homologous chromosomes.
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2 sets of chromosomes
Diploid
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1 set of chromosomes
Haploid
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What is the diploid number of chromosomes in humans?
46
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What is the haploid number of chomromosomes in humans?
23
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Diploid fertilized egg
Zygote
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Chomromosomes not involved in determining sex.
Autosomes
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Chromosomes that determine sex.
Sex chromosomes
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How many autosomes are in a human somatic cell?
44 (22 pairs)
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How many sex chromosomes are in a human somatic cell?
2 (1 pair)
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How many autosomes are there in a human gamete?
22
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How many sex chromomes are in a human gamete?
1
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What are the sex chromosomes for a human female?
XX
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What are the sex chromosomes for a human male?
XY
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Phase of meiosis in which chromosomes form tetrads, crossing over occurs, nuclear envelope breaks down, and spindle fibers form.
Prophase I
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Phase in meiosis in which homologous chromosomes line up double file in the middle at the equator
Metaphase I
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Phase of meiosis in which homologous chromosomes are pulled apart to opposite poles
Anaphase I
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Phase in meiosos in which nuclear envelope reforms, cell divides into 2 cells, chromosome number is now cut in half.
Telophase I/Cytokinesis
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Phase of meiosis in which nuclear envelope breaks down and spindle fibers form. Occurrs in 2 cells.
Prophase II
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Phase in meiosis in which chromosomes line up single file in the middle of the cell at the equator.
Metaphase II
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Phase of meiosis in which sister chromatids separate to opposite poles.
Anaphase II
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Phase of meiosis in which chromosomes uncoil into chromatin, the nuclear envelope reforms and the 2 cells split into 4
Telophase II/Cytokinesis
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Structure that forms when homologous chromosomes pair up (XX or xx)
tetrads
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Occurs during Prophase I. Homologous chromosomes exhange pieces of DNA
crossing over
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Random organization of the chromosomes at the equator
Independant assortment
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Where does meiosis occur in humans?
Testes and ovaries
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Formation of sperm by meiosis
Spermatogenesis
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Formation of eggs by meiosis
Oogenesis
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A mutation in which a piece of chromosome breaks off.
Deletion
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Mutation that occurs during crossing over and instead of exchanging pieces equally, one chromosome has a section delted and this section is added to the homologous chromosome.
Duplication deletion mutation.
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Mutation in which a chromosome piece reattaches to original chromosome but in reverse orientation.
Inversion mutation
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Mutation in which a chromome piece attaches itself to a nonhomologous chromosome
Translocation mutation
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Proper separation of chromosomes during meiosis
Disjunction
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Failure of chromosomes to separate during meiosis resulting in too many or too few chromosomes in the gametes.
Nondisjuction
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Picture of the chromosome in a cell that is used to check for abnormalities.
Karyotype
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How does a person get too many or too few copies of a chromosome?
Nondisjunction
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Humans with 3 copies of one chromosome
Trisomy
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In which cells does mitosis occur?
Somatic cells (body cells)
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What type of cells are formed during meiosis?
Gametes (sex cells)
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Is mitosis involved in sexual or asexual reproduction?
asexual reproduction
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Is meiosis involved in sexual or asexual reproduction?
sexual reproduction
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how many times does the nucleus divide in mitosis?
1
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How many times does the nucleus divide in meiosis?
2
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Are the cells diploid or haploid at the beginning of mitosis?
Diploid
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Are the cells diploid or haploid at the beginning of meiosis?
Diploid
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Are the cells diploid or haploid at the end of mitosis?
Diploid
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Are the cells diploid or haploid at the end of meiosis?
Haploid
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What are the advantages of mitosis?
Quick process and little energy needed
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What are the advantages of meiosis?
Genetic diversity
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What are the disadvantages of mitosis?
No genetic diversity
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What are the disadvantages of meiosis?
Takes time and energy
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How many cells are produces at the end of mitosis?
2
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How many cells are produced at the end of meiosis?
4
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How are sister chromatids related?
They contain identical copies of DNA
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