Science

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Chromatin

Back 1

A loose form of DNA

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Chromosome

Back 2

condensed DNA that is shaped like an "X" with a centromere at the center. Each half is a chromatid.

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Interphase

Back 3

When the cell is not dividing (is split up into multiple phases)

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Cell division phase

Back 4

Mitosis (division of DNA) and Cytokineses (division of everything else) take place

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G1 Phase

Back 5

Cell is smaller, and is preparing for synthesis. Synthesizes mRNA and proteins in preparation for the next steps leading to mitosis

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Synthesis

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Replication of DNA and centrisomes, and cell growth

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G2 Phase

Back 7

more growth and cell continues to produce proteins. The cell is preparing for division (synthesizing lots of microtubules)

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Chromatid

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Half of a chromasome

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Kinetochore

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A handle in the chromosomes for the microtubules to grab onto. They are attached too each side of the sister chromatid.

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Centrosome

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Where microtubules are organised

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kinetochore microtubials

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connected to the centrosomes on one end and the chromosomes at the other via the kinetochores

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Prophase

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chromatin condenses into chromosomes, nucleolus disappears, microtubule assembly begins.

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Prometaphase

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Nuclear membrane breaks down, kinetochore microtubules form and start to attach to the kinetochores, polar microtubules push against each other to push the centrosomes apart and astral microtubules are made to anchor the centrosomes in place at opposite polls.

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Metaphase

Back 14

Chromosomes line up in the middle of the cell (what is called the metaphase plate)

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Anaphase

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Chromosomes break into chromatids and begin to go towards separate polls

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Telophase

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Chromatids begin to decondense into chromatin, nuclear membranes form around the chromatin, in plants new cell walls begin to form and in animals a cleavage furrow forms

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Cytokenesis

Back 17

The cell seperates into two

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Astral microtubules

Back 18

act like pegs to hold down the centrosomes (stakes for a tent)

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Transcription

Back 19

RNA polymeraseattaches to the start of a transcription unit (the TATA box) making a strand of mRNA out of free bases in the nucleus. The DNA is made up of protiens and these bases match up with these protiens

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Translation

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Ribosomes bind to the messenger RNA to produce a chain made up of amino acids carried by tRNA that is read 3 bases at a time, and as each triplet is read a tRNA delivers the corresponding amino acid this is added to a growing chain of amino acids which folds to form a protein.

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TATA box

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A sequence of adenine, thymine, cytosine and guanine just above a transcription unit (or upstream as biologists call it)

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Transcription unit

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The length of DNA that is going to be transcribed on an RNA molecule

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RNA polymerase

Back 23

copies the DNA sequence downstream from the TATA box until it reaches a termination signal into a similar mRNA

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RNA splicing

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unneeded information from the mRNA is taken out before exiting the nucleus

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Snurps

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combination of RNA and proteins that recognize the start and the end of areas to be spliced

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Spliceosome

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the snurps form together with a bunch of other proteins to do the actual splicing of the mRNA

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TACG how they match up

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T-A

C-G

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DNA replication

Back 28

Helicase unzips the DNA and creates a replication fork (the double helix being separated). These separated strands are templates for a new strand of DNA. Primase makes a primer which then the DNA polymerase binds to the primer and creates the DNA. Exonuclease then removes the primers and then another DNA polymerase enzyme fills in the gaps. Finally ligase seals up the DNA.

Front 29

Helicase

Back 29

The enzyme that unzips the DNA

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Primase

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Makes the Primer

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Primer

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A small piece of RNA that marks the starting point for the construction of the DNA

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DNA polymerase

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Binds to the primer and creates the new DNA strand by using the matching bases (A-T, C-G)

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Exonuclease

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an enzyme that removes the primers

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Ligase

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Seals the fragments of DNA

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Oxygen transport in blood (getting the oxygen)

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The first part is the taking up of oxygen by blood flowing through capillaries in the walls of the lungs air sacs or alveoli. The oxygen molecules change from a gas dissolving into a solution in the plasma that transports 98% of this oxygen to passing red blood cells leaving just 2% remaining in the solution.

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capillaries

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A capillary is an extremely small blood vessel located within the tissues of the body, that transports blood from arteries to veins.

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alveoli

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the walls of the lungs air sacs.

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hemoglobin

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an oxygen binding protein found in red blood cells

hemoglobin contains 4 molecules of heme, an iron containing pigment that binds oxygen loosely and reversibly.

When fully saturated with oxygen turns a bright red colour as opposed to the darker red non saturated hemoglobin.

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oxyhemoglobin

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hemoglobin that is saturated with oxygen

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Oxygen transport in blood (depositing the oxygen)

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the hemoglobin give up oxygen when red blood cells travel through capillaries where there is a low content (partial pressure) of oxygen. The partial pressure of oxygen represents the level of dissolved oxygen in plasma. As oxygen is released and becomes part of the solution again, the partial pressure of oxygen in the capillaries becomes greater than the partial pressure of oxygen in the surrounding tissues. This causes oxygen to move out of the capillaries, into the tissues and to finally reach the cells.