Can anyone plz explain me the difference b/t a phenotype and a genotype; dominant and recessive.?

Question

Also, I'm confused of what's different of a homologous chromosome and a sister chromatid/non-sister chromatid. I need to clear these things up b4 the test. Appreciate it. Thnks

Answer 1

Phenotype is the characteristic, behavior, trait that the individual has. (PKU, colorblindness, straight wings, ...)
Genotype is the combination of alleles -- or the kinds of genes the individual has. (Pp, BB, bb, ...)

I tell my students that phenotype is the FORM that they have - and exaggerate the F sound on the beginnings of the words phenotype and form. So genotype is what the genes say.

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Dominant forms of a gene are the ones that show up even if there's just one of them. (BB and Bb will both show the dominant phenotype because they each have at least one uppercase B.)
Recessive forms of a gene are the ones that only show up if there's no dominant one to keep them from showing. (bb lets the recessive phenotype show because there's no uppercase B to keep it the recessive trait from showing.)

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Homologous chromosomes are the two chromosomes that match - one from each parent. If you've seen a picture of a person's chromosomes all lined up from longest to shortest, you'll see that they are arranged in pairs in the picture. The first pair is called #1, and a person has two #1 chromosomes -- one from Mom and one from Dad. Those two are homologous because they have genes about the same traits. The genes might not agree, but they're telling about the same traits. Remember that the prefix "homo-" means "same" (homologous = same-ologous)

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Sister chromatids are the two sides of a double-stranded chromosome. You know how chromosomes that are ready for mitosis or meiosis look like clothespins or pliers? The left-hand side or string is one sister chromatid, and the right-hand string is the other sister chromatid. The two sister chromatids are held together at the centromere. They are exact copies of each other because one is the original DNA that was copied.

Non-sister chromatids are chromatids that are on different chromosomes. They are NOT held together by centromeres because they are parts of different chromosomes from each other.

Answer 2

I'm going to give these in a slightly different order as I think it makes more sense. The gene codes for the character, or more correctly the protein. In your example the gene codes for one of the globin proteins that makes up a molecule of haemoglobin. Genes have different alleles, which are variants of the gene. In your example, the normal allele will code for a normal globin and the thalassaemia allele codes for an abnormal globin protein and may lead to disease. Alleles may be dominant, recessive (or co-dominant). A dominant allele is always expressed when it is present and a recessive is only expressed when there are two copies. In your example the normal allele (T) is dominant. Whenever at least one T allele is present then you will have normal haemoglobin. The thalassaemia allele is recessive you need 2 copies to have the disease. The reason that this is the case is that, although both alleles will be converted in proteins, there will be enough normal copies produced so that haemoglobin molecules can be properly synthesised and so anyone carrying only one copy of the t allele will appear normal with respect to haemoglobin. Finally genotype and phenotype. The genotype is the actual combination of alleles. In your example there are four possibilities TT, Tt, tT and tt. The middle two are functionally the same, but there are two ways of inheriting this combination, depending on which parent donates which allele. Phenotype is the character state, you are either normal for this trait or you have thalassaemia so there are only two possibilities. Genotypes TT, Tt and tT produce a normal phenotype and tt produces thalassaemia. Hope that helps!

Answer 3

Phenotype- The phenotype of an individual organism is either its total physical appearance and constitution or a specific manifestation of a trait, such as size, eye color, or behavior that varies between individuals. Many phenotypes are determined by multiple genes and influenced by environmental factors.

Genotype- The genotype is the specific genetic makeup (the specific genome) of an individual, in the form of DNA. Together with the environmental variation that influences the individual, it codes for the phenotype of that individual.

Dominant- refers to a genetic feature that hides the recessive trait. A dominant trait causes a phenotype that is seen in a heterozygous genotype. Many traits are determined by pairs of complementary genes, each inherited from a single parent.

Recessive- refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele) and never in a heterozygous genotype. Every person has two copies of every gene on autosomal chromosomes, one from mother and one from father

Homologous chromosome- are chromosomes in a biological cell that pair (synapse) during meiosis, or alternatively, non-identical chromosomes that contain information for the same biological features and contain the same genes at the same loci but possibly different genetic information, called alleles, at those genes. For example, two chromosomes may have genes encoding eye color, but one may code for brown eyes, the other for blue.

Sister chromatid- are identical copies of a chromosome

Answer 4

phenotype : set of visible and in visible traits
- morphological
- biochemical
- physiological
genotype : is the traits that reveal the phenotype
dominant is only allele that is expressed in hetroztgote
recessive is allele that is expressed in homozygote
homologous chromosome is the chromosomes that have same length
same bands, and same position in centromere on the two chromosomes
sister chromatid : the chromosome have two sister chromatid
like two stick attached by gum this gum is centromere and the
non-sister chromatid its two different stick came from different chromosome but the two stick never be attached