Meiosis phase one (UEB Uncontracted)
By:
Sign Up Now!
Already a Member? Log In
You must be logged into UK education collection to access this title.
Learn about membership options,
or view our freely available titles.
- Synopsis
- These pages show late interphase before meiosis, and five stages of meiosis phase one. There is a locator dot shown on each page, which will be at the top left of the page when the image is the correct way up. Meiosis is cell replication where a cell divides to produce four non-identical gametes, each with only one set of chromosomes instead of the usual two sets found in all other cells.Late interphase before meiosis. This page shows a cell immediately before meiosis starts. The cell is a large rounded shape in the centre of the page. Its nucleus fills the bottom of the cell and two centrioles are in the top of the cell. The twenty three pairs of chromosomes in the nucleus have replicated to form a mass of chromatids (double chromosomes) which are tightly coiled. Note the size of the nucleus and the centrioles in relation to the overall size of the cell are greatly enlarged for clarity. Only some of the chromatin is shown, also for clarity. Meiosis - stage one, early prophase I. This page shows the start of meiosis. The cell is in the centre of the page. In the top of the cell the centrioles to the left and right have the mitotic spindle growing between them. The nucleus shows two chromatids - the double chromosomes. The ends of the chromosomes of the chromatids are crossed in two places, to the top and bottom of the pair. In reality in humans there would be twenty three pairs of chromatids.Meiosis - stage one, late prophase I. This page shows chromatids after crossover. The cell is in the centre of the page. In the top of the cell the centrioles to the left and right have the mitotic spindle growing between them. The nucleus shows two chromatids - the double chromosomes. The ends of the chromosomes of the chromatids have swapped DNA coding where they were crossed. The ends to the top centre of the chromatids have swapped and the ends of the other pair of chromosomes to the bottom centre have also swapped.Meiosis - stage two, metaphase I. This page shows the completed mitotic spindle with a centriole to the left and right. The nuclear envelope has disappeared. The chromatids have attached themselves side by side to the centre of the spindle on the central microtubule by their centromeres in the centre of the image. For clarity other chromatids are not shown so the microtubule to the top and bottom of the image appears empty. In reality there would be many more pairs of chromatids and microtubules.Meiosis - stage three, anaphase I. This page shows the centromeres have separated. The microtubules of the spindle are retracting to the left and right. Each chromatid of the pair of chromosomes are migrating to opposite ends of the spindle to the left and right.Meiosis - stage four, telophase I. This page shows centrioles to the left and to the right. One chromatid is in the left and one chromatid is in the right of the cell. To the top and bottom centre of the cell the plasma membrane is pinching in and starting to divide the cytoplasm.
- Copyright:
- 2017
Book Details
- Book Quality:
- Publisher Quality
- Publisher:
- RNIB Bookshare
- Date of Addition:
- 01/01/17
- Copyrighted By:
- RNIB Bookshare
- Adult content:
- No
- Language:
- English
- Has Image Descriptions:
- No
- Categories:
- Nonfiction, Science
- Grade Levels:
- Year 10 - 4th Form - KS4, Year 11 - 5th Form - KS4
- Submitted By:
- Bookshare Staff
- Usage Restrictions:
- This is a copyrighted book.