Genetics 3.2 Chromosomes Flashcards
Compare eukaryotic and prokaryotic chromosomes
Prokaryotes have one chromosome consisting of a circular DNA molecule. Eukaryotes have chromosomes that have linear DNA molecules.
Prokaryotic DNA is naked. Eukaryotic DNA molecules are wrapped around histone proteins.
The circular prokaryotic chromosome contains all genes.. Eukaryotes have different chromosomes with different genes.
Prokaryotes sometimes have plasmids. Eukaryotes do not.
What are homologous chromosomes?
Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles.
What are diploid nuclei?
A diploid nucleus contain two copies of each homologous chromosome/ have pairs of homologous chromosome/ two chromosomes of each type.
number of chromosomes = 2N
What are haploid nuclei?
A haploid nuclei has one chromosome of each homologous chromosome.
number of chromosomes = N
What was used to establish the length of DNA molecules?
Due to developments in scientific research, improvements were made in their techniques that included using autoradiography to establish the length of DNA molecules in chromosomes as they discovered specific substances located in cells/tissues.
What does the number of chromosomes indicate?
Number of chromosomes is a characteristic feature of members of a species.
How are genders determined on a karyogram?
Gender is determined by sex chromosomes.
What are autosomal chromosomes?
Autosomal chromosomes are chromosomes that determine the sex. (1st to 22nd Pair)
What can we deduce on a karyogram of an unborn baby?
We can identify the gender.
We can identify chromosomal abnormalities in health.
What is a karyogram?
Karyograms show the chromosomes of an organism in homologous pairs of decreasing length
How can you diagnose Down syndrome and what its syndromes?
If there are three copies of chromosome 21 instead of two, the individual as down syndrome.
Some of the component features of the syndrome are hearing loss, heart and vision disorder. Mental and growth retardation are also very common.
Outline Cairns technique for measuring the length of DNA molecules.
- radioactively labelled chromosomes of the DNA by growing them in a medium containing thymidine
- Using an enzyme cell walls were digested so that cells could release their DNA
- a thin film of photographic emulsion was applied to the membrane so that when DNA decayed, it reacted with the film
- Dark grains are seen where DNA decayed which indicates the position.
What are Pan troglodytes?
Chimpanzees
What are Canis familiaris
Dogs
What are the methods to collect cells from embryo for karyotyping?
Amniocentesis and chorionic villus sampling are two methods to collect the amniotic fluid.
