Help appreciated!
Please do not give a copy/pasted version from wikipedia. I've already tried that website, but hoping someone can explain and make it more clear.
Thanksss!!
:-)
2006-11-15 21:20:55 · 5 answers · asked by Miss. Me 2 in Science & Mathematics ➔ Biology
They share just about everything - size, morphology (metacentric, submetacentric or acrocentric) and banding pattern at metaphase (see http://members.aol.com/chrominfo/geninfo.htm for a nice quick explanation of these things).
What will not be shared will be minute variations in the exact sequence of the DNA, given that half of the sequence will orginate from the mother and half from the father. These genetic differences account for phenotypic (physical) differences following expression of all the genes and contribute to the fact that your parents are not identical.
2006-11-15 22:34:48 · answer #1 · answered by Alyosha 4 · 1⤊ 0⤋
I think that 2 homologous chromosomes share all characteristics as they are composed of the same 2 genes (either dominant or recessive e.g. TT and tt). So the genotype is the same. The phenotype will probably be the same also but there are some phenotypes that are environment dependent.
This is all as far as I understand it in a simple way-hope it helps!
2006-11-16 05:26:40 · answer #2 · answered by Charlotte C 3 · 0⤊ 0⤋
Autosomes; homologous chromosomes, one from each parent (humans = 22 sets of 2)
Female-sex chromosomes are homologous (XX)
Male-sex chromosomes are non-homologous (XY)
Prophase I
DNA replication precedes the start of meiosis I. During prophase I, homologous chromosomes pair and form synapses, a step unique to meiosis. The paired chromosomes are called bivalents.
Prometaphase I
The nuclear membrane disappears. One kinetochore forms per chromosome rather than one per chromatid, and the chromosomes attached to spindle fibers begin to move.
Metaphase I
Bivalents, each composed of two chromosomes (four chromatids) align at the metaphase plate. The orientation is random, with either parental homologue on a side. This means that there is a 50-50 chance for the daughter cells to get either the mother's or father's homologue for each chromosome.
Anaphase I
Chiasmata separate. Chromosomes, each with two chromatids, move to separate poles. Each of the daughter cells is now haploid (23 chromosomes), but each chromosome has two chromatids.
Telophase I
Nuclear envelopes may reform, or the cell may quickly start meiosis II.
Cytokinesis
Analogous to mitosis where two complete daughter cells form.
Meiosis II is similar to mitosis. However, there is no "S" phase. The chromatids of each chromosome are no longer identical because of recombination. Meiosis II separates the chromatids producing two daughter cells each with 23 chromosomes (haploid), and each chromosome has only one chromatid.
Comparing Meiosis and Mitosis
Chromosome behavior
Mitosis: Homologous chromosomes independent
Meiosis: Homologous chromosomes pair forming bivalents until anaphase I
Chromosome number- reduction in meiosis
Mitosis- identical daughter cells
Meiosis- daughter cells haploid
Genetic identity of progeny:
Mitosis: identical daughter cells
Meiosis: daughter cells have new assortment of parental chromosomes
Meiosis: chromatids not identical, crossing over
Mitosis, Meiosis, and Ploidy
Mitosis can proceed independent of ploidy of cell, homologous chromosomes behave independently
Meiosis can only proceed if the nucleus contains an even number of chromosomes (diploid, tetraploid).
The link also has animated explanations.
2006-11-16 05:54:16 · answer #3 · answered by Chariotmender 7 · 0⤊ 0⤋
Same length, same structure, same gene loci, same position of centromere.
2006-11-16 07:21:08 · answer #4 · answered by Moo i'm a cow 2 · 0⤊ 0⤋
Is it that they both have a dark blue hat?
2006-11-16 05:23:25 · answer #5 · answered by Anonymous · 0⤊ 1⤋