Lesson 3 nucleus dna-chromosomes

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To what extent can our genetics determine what we can be in life?

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nucleus dna-chromosomes

Transcript of Lesson 3 nucleus dna-chromosomes

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To what extent can our genetics determine what we can be in life?

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DNA: Chromatin, chromosomes

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Molecules that contain the all the genetic information of theindividual.

Depending on how packed the DNA is we talk about:

Chromatin: DNA molecules are more spread out in the nucleoplasm. DNA is normally in this state.

Chromosomes: DNA molecules are highly coiled and packed formingspecific structures. DNA only coils into chromosomes when the cell is goingto divide.

The DNA molecules are made up of a sequence of bases which formcodes.

These codes are the intructions for the formation of proteins. Proteins are responsable for carrying out all metabolic processes.

Each complete code that codifies for a protein is called a gene.

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When the DNA packs the resulting chromosome has 2 sister chromatids.

Sister chromatids: identical copies of a DNA molecule.

Each chromatid has 2 arms (p and q)

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All human somatic cells have 46 chromosomes (23 pairs) or 2 sets (2n)

Diploid cells (2n): cells with pairs of chromosomes.

The pair is made up by Homologous chromosomes.

Chromosomes that carry the same genes, but not necessarily the samegenetic information.

They have the same shape and structure, and banding.

Human gamets have 23 chromosomes in total. Only one set of chromosomes (n).

Haploid cells(n): cells with only one chromosome of each type

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Each specie has a specific number of different chromosomes (n)

Their somatic cells have pairs of chromosomes 2n

Their gametes have only one set of chromosomes (n)

Calculate the haploid number (n)

for each species: (2n)

Worksheet

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Carry same genes in the same locus, but with different (or not) information for each of the genes.

Somatic cells (diploid cells) carry 2 pieces of information for each gene. 2 chromosomes of each type.

One inherited from the mother and the other from the father.

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Chromosomes have the peculiar property of staining in bands, or chromosome segments, allowing the precise identification of individual chromosomes or parts of chromosomes.

Definition from: MeSH via Unified Medical Language System at the National Library of Medicine

The chromosomes are visualized as consisting of a continuous series of bright and dark bands.

These bands are always the same in each chromosome, because the position of the genes and therefore bases in the DNA is always the same.

The specific position of a gene is called the gene locus.

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Organized positioning of chromosomes extracted from a cell.

by size, structure and centromere position, and bands

Gives information on the number of chromosomes of an organism.

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Human karyotype: (somatic cell)

Shows 23 pairs of chromosomes in total

22 pairs of autosomes and 1 pair of sex chromosomes.

Sex chromosome pair can be:

XX : in females

XY: in males

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1. Is it genetic material of a diploid or haploid cell?

2. Is it genetic material of a uman or non human cell?

3. Is it genetic material of a male or female individual?

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1. Is it genetic material of a diploid or haploid cell?

2. Is it genetic material of a human or non human cell?

3. Is it genetic material of a male or female individual?