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Meiosis - Building Directory
Meiosis - Building Directory

... passes copies of all its genes on to its offspring Since the offspring has the same genetic info as its parent, it is known as a clone The only genetic variation is due to mutations ...
karyotypes - TeacherWeb
karyotypes - TeacherWeb

... Too many or too few chromosomes Sometimes chromosomes are incorrectly distributed into the egg or sperm cells during meiosis. This can result in an abnormal number of chromosomes. If a sperm with an extra chromosome fertilizes an egg with a normal chromosome number, the resulting zygote will have 3 ...
Lecture 36 “Genes, Development, and Evolution” PPT Review What
Lecture 36 “Genes, Development, and Evolution” PPT Review What

... must be expressed for the ribs to form? Using this, why are there no forelimbs in snakes? 3.) Snake example: what would cause them to “lose” their hindlimbs? When this pathway is functioning “normally”, what is its immediate function? 4.) Through what type of cell communication pathway does SHH func ...
Exam practice answers 8
Exam practice answers 8

... (iii) If the chiasma forms between non-sister chromatids, the alleles on homologous chromosomes can be exchanged. This produces new combinations of alleles in the gametes. New combinations of alleles mean that there is genetic variation. Selection can occur and the species can evolve to meet the nee ...
11-4-15 SI Session Answers
11-4-15 SI Session Answers

... Alleles  Different  variations  of  the  same  gene;  usually  denoted  with  an  uppercase  letter  or  a  lowercase  letter   Gene  A  unit  of  heredity  that  is  passed  down  from  parent  to  offspring   Independent  Assortment   ...
Slide 1
Slide 1

... Standards 2a. Know meiosis is an early step in sexual reproduction in which the pairs of chromosomes separate & segregate randomly during cell division to produce gametes containing 1 chromosome each. 2b. Know only diploid cells, spermatogonia & oogonia undergo meiosis. 2c. Know random chromosomal s ...
Meiosis - Grant County Schools
Meiosis - Grant County Schools

... Interphase – just like interphase of Mitosis the cell replicates its chromosomes (2 identical sister chromatids held together by a centromere) Prophase I – The chromosomes coil up and the spindles form. Each pair of homologous chromosomes come together, matched gene by gene (forms a four part struct ...
Genes and Chromosomes worksheet
Genes and Chromosomes worksheet

... This can happen during: and ...
CH 13 NOTES – Meiosis
CH 13 NOTES – Meiosis

... 2) At the metaphase plate, there are paired homologous chromosomes (tetrads), instead of individual replicated chromosomes 3) At anaphase I, it is homologous chromosomes, instead of sister chromatids, that separate and are carried to opposite poles of the cell ...
You and Your Genes Revision Lesson 1
You and Your Genes Revision Lesson 1

... Different versions of genes are called alleles. Our mix of alleles determines what we are like. Most characteristics are due to a number of genes. Some are due to only one gene, and some are affected by environment. ...
Show Me the Genes KEY
Show Me the Genes KEY

... The offspring receive half of their chromosomes from each parent just like in Mendel’s model. 8. We know that parents make “copies” of their genetic information to pass to their offspring. Why do the egg and sperm contain only 23 chromosomes? Each sex cell has 23 chromosomes because when they unite, ...
Sexual Reproduction
Sexual Reproduction

... In females, 4 cells are produced, but only one will become an egg cell. All of the cytoplasm and all of the organelles are put into one egg cell. The other three cells will ...
Genetics - Cloudfront.net
Genetics - Cloudfront.net

... generated in a zygote through the fusion of male and female gametes (fertilization) e. why approximately half of an individual’s DNA sequence comes from each parent f. the role of chromosomes in determining an individual’s sex g. how to predict possible combinations of alleles in a zygote from the m ...
meiosis - lhsbiocaine
meiosis - lhsbiocaine

...  Human somatic cells (those not used for reproduction) have 46 chromosomes  A chromatid has a complete set of an organisms DNA  A chromosome has 2 copies of that set  This is called a “diploid number” of chromosomes (2x) ...
RG 2.0 - mitosis and..
RG 2.0 - mitosis and..

... The two chromatids separate and move to opposite poles of the cell. ...
General Biology Chapter 5 Homework Meiosis This is the homework
General Biology Chapter 5 Homework Meiosis This is the homework

... diploid reproductive cell and make four haploid gametes for sexual reproduction. 2. How many times does the cell divide in meiosis? There are 2 cell divisions in Meiosis. 3. What is the ploidy (sets of chromosomes) of cells before and after meiosis? In humans the reproductive cell at the beginning i ...
Document
Document

... If there are chromosomal number abnormalities, how do they form? • Meiosis: the process of creating sperm or egg from a diploid cell • If there is a mistake when chromosomes are separating, then the resulting sperm or egg will have too many or too few chromosomes. ...
File
File

... • Parents pass on genes to their offspring • Genes program specific traits that emerge as we develop from fertilized eggs into adults. – Example: Your may have a gene for blue eyes, which you inherited from your mother. ...
Name - Piscataway High School
Name - Piscataway High School

... Recessive – the allele that is only expressed when two copies are present Answer the following questions in complete sentences. How are the terms genes, locus and allele related? All have something to do with a particular segment of DNA, or nucleotides. A gene is a region of DNA, a series of nucleo ...
Meiosis
Meiosis

... • Homologous chromosomes contain the same genes, ...
Meiosis
Meiosis

... How many chromosomes do we have in body cells? How many chromosomes do we have in sex cells? If your parents have 46 chromosomes in their cells, do you have 92 chromosomes in your cells? ...
Lecture 5
Lecture 5

... Males will not have a Barr body In cats it is possible to see that condensation of the X in females is random. The way to do this is to have variation in a gene on the X chromosome. ...
Study Guide- DNA, Protein Synthesis, Mitosis and Meiosis
Study Guide- DNA, Protein Synthesis, Mitosis and Meiosis

... plate, somatic cells, gametes, chromosome number, diploid and haploid 13) Diagram the events in the cell cycle, including the three stages of interphase and the four stages of mitosis. 14) Discuss how molecular “brakes” function to inhibit cancerous tumors. 15) Compare and contrast cancerous and non ...
Genes, Alleles, and Meiosis PowerPoint
Genes, Alleles, and Meiosis PowerPoint

... • Each of a human’s 46 chromosomes has thousands of genes, so the presence of all chromosomes is essential for normal functioning Humans who are missing a chromosome don’t survive past the embryo stage Humans with more than two copies of a chromosome may survive but will not develop properly (this ...
File
File

... diploid cells – similar in shape, structure, and size and have the same genes, but not necessarily the same alleles. ...
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Ploidy



Ploidy is the number of sets of chromosomes in a cell. Usually a gamete (sperm or egg, which fuse into a single cell during the fertilization phase of sexual reproduction) carries a full set of chromosomes that includes a single copy of each chromosome, as aneuploidy generally leads to severe genetic disease in the offspring. The gametic or haploid number (n) is the number of chromosomes in a gamete. Two gametes form a diploid zygote with twice this number (2n, the zygotic or diploid number) i.e. two copies of autosomal chromosomes. For humans, a diploid species, n = 23. A typical human somatic cell contains 46 chromosomes: 2 complete haploid sets, which make up 23 homologous chromosome pairs.Because chromosome number is generally reduced only by the specialized process of meiosis, the somatic cells of the body inherit and maintain the chromosome number of the zygote. However, in many situations somatic cells double their copy number by means of endoreduplication as an aspect of cellular differentiation. For example, the hearts of two-year-old children contain 85% diploid and 15% tetraploid nuclei, but by 12 years of age the proportions become approximately equal, and adults examined contained 27% diploid, 71% tetraploid and 2% octaploid nuclei.Cells are described according to the number of sets present (the ploidy level): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc. The generic term polyploid is frequently used to describe cells with three or more sets of chromosomes (triploid or higher ploidy).
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