This document includes notes on chromosomes and meiosis as well as a one page summary. Theses notes are very detailed and easy to understand, and the summary is the perfect tool for revision.
like structures that form part of the chromatin network in the
↳ made
up of a strand of DNA wound around proteins called histones
dye very easily (chromosomes
↳ absorb coloured bodies) which visible
makes them
-
,
seen as individual threads cell
under a
microscope but are
only when is dividing
↳ a short
piece of DNA in a chromosome comprises a
gene ,
which is a
hereditary
Unit consisting of a
sequence of DNA that occupies a specific location on a
and determines in
chromosome a
particular characteristic an
organism
↳ when
as a thread (chromatin network )
a cell is not
dividing ,
the chromosomes appear
↳
When a cell divides ,
the chromatin network condenses ,
the threads shorten ,
thicken
and become visible as chromosomes
In somatic (
body) cells of diploid organisms :
Number of chromosomes in each cell is the same
-
'
Chromosomes are made of two sets; maternal and paternal chromosomes ,
therefore called
diploid cells 12h
For maternal chromosome
each paternal chromosome there is
matching forming
-
a a
same
homologous pair The .
chromosomes in the
pair are then size ,
shape and
carry genes for the
same hereditary characters ,
but
may carry
a different form of the characteristic
alternative forms of the are called alleles
gene
Chromosome number
↳ each
species has a specific number of chromosomes in its somatic cells ,
which is not
related to the size
complexity of the species
↳ with identical numbers, have similarities in the DNA
organisms may
,purpose is to separate the homologous In humans : diploid number -
46
pairs so each gamete will possess one
,
haploid number -
23
chromosome of each homologous pair
meiosis ( reduction division )
↳ cell division that
takes place in the reproductive
organs of plants and animals to
produce gametes
The reduced from kn ) in the cell to one
-
number of chromosomes is two sets parent
set ( n ) in each of the cells formed ( number of chromosomes is halved )
daughter
The normal number of chromosomes in cells is called the diploid number
'
The gametes l spores formed are called haploid have of chromosomes
they one set
-
as
( one chromosome from each homologous pair )
↳
when two haploid gamete fuse , the diploid number is restored ( male haploid gamete t
female haploid gamete =
diploid zygote)
↳
zygote divides by mitosis ,
every somatic cell contains the diploid number of chromosomes
↳ in
that reproduce the number of chromosomes is
organisms sexually ,
always an even
number because it consists of two sets of chromosomes ( one from each
gamete )
↳ without
meiosis the number of chromosomes would double with each
generation
where does meiosis take ?
place
↳ in animals testis and ovaries
it takes place in the reproductive organs ,
spermatogenesis formation of sperm
-
cells in testis
-
oogenesis formation of cells lov a in ovaries
-
egg
-
↳ in
plants it takes place in the formation of spores in sporangia
In seed plants
bearing
-
:
-
micro are the pollen sacs in the male anthers
sporangia
in the
megasporangia
.
are the ovules female ovaries
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller sadepeleowo. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.47. You're not tied to anything after your purchase.
