unit 2 biology

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what is the first step of DNA repliaction?
DNA helicase breaks H bonds between the 2 polynucleotide DNA strands. Helix unzips to form 2 single strands
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what is the second step of DNA repliaction?
Each single strand acts as template for new strand. Free floating nucleotides join to bases on each strand by specific base pairing
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what is the third step of DNA repliaction?
Nucleotides on new strand joined together by DNA polymerase. H bonds form between original and new strand.
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what is interphase?
period of cell growth and DNA replication. Split into 3 growth stages of G1 S1 and G2
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what happens during G1?
cells grow and new organelles and proteins are made
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what happens during synthesis?
cell replicates its DNA ready to divide by mitosis
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what happens during G2?
cells keep growing and proteins needed for cell division are made
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what are the 4 stages of mitosis?
prophase, metaphase, anaphase, telophase
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what happens during prophase?
chromosomes condense getting shorter and fatter. Centrioles start moving to opposite ends of the cell, forming spindle. Nuclear envelope breaks down, chromosomes lie free in cytoplasm.
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what happens during metaphase?
chromosomes line along middle of cell, become attached to spindle by centromere
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what happens during anaphase?
centromeres divide separating each pair of sister chromatids. Spindles contract pulling chromatids to opposite ends of the cell, centromere first
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what happens during telophase?
chromatids reach opposite poles on spindle, uncoil and become long and thin again, nuclear envelope forms around each group of chromosomes, now 2 nuclei. Cytoplasm divides and there are now 2 genetically identical daughter cells
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what's cancer?
uncontrolled cell division
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describe a cancer treatment.
Some treatments are designed to interrupt the cell cycle. Target rapidly dividing cells, this kills tumour cells and some normal cells.
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what's chemotherapy?
Chemotherapy prevents the synthesis of enzymes needed for DNA replication. If these aren’t produced the cell is unable to enter the S phase, forcing the cells to kill itself
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what's radiation?
Radiation and some drugs damage DNA. When cells get to S phase it checks for damaged DNA and if it detects any it kills itself, preventing further tumour growth
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what's the process of becoming specialised?
differentiation
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what are tissues?
similar cells grouped together
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what's an organ?
group of different tissues that work together to perform a particular function
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Card 2

Front

what is the second step of DNA repliaction?

Back

Each single strand acts as template for new strand. Free floating nucleotides join to bases on each strand by specific base pairing

Card 3

Front

what is the third step of DNA repliaction?

Back

Preview of the front of card 3

Card 4

Front

what is interphase?

Back

Preview of the front of card 4

Card 5

Front

what happens during G1?

Back

Preview of the front of card 5
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