Y10 Biology - Genetics and Chromosomes

DNA

Genetic material passed down through generations, stored in the nucleas of a cell.

How do nucleotides bond?

They use covalent bonds to bond sugar to phosphate and hydrogen bonds to bond base to base.

Female Chromosomes

two X chromosomes, one maternal one paternal

Male Chromosomes

one X chromosome (maternal) one Y chromosome (one paternal)

Number of chromosomes

46 (23 pairs), first 22 pairs are autosomal, 23rd are sexual

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits.

Mitosis

cell division in order to grow or repair

Meiosis

cell division to produce gametes

Heterozygous

having two different alleles for a trait

Homozygous

two of the same alleles for a trait

Interphase

Cell grows, performs its normal functions, and prepares for division by duplicating

Prophase

The first stage of mitosis where chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and spindle fibers begin to form.

Metaphase

The second stage of mitosis characterized by the alignment of chromosomes along the metaphase plate, ensuring proper separation.

Anaphase

The third stage of mitosis where sister chromatids are pulled apart to opposite poles of the cell by the spindle fibers.

Telophase

The final stage of mitosis where chromosomes de-condense back into chromatin, the nuclear envelope re-forms, and the cell prepares to divide.

Cytokinesis in Mitosis

The process that follows mitosis, where the cytoplasm divides, resulting in two separate daughter cells.

Prophase I

The first stage of meiosis where homologous chromosomes pair up and exchange genetic material through crossing over.

Metaphase I

The stage of meiosis where homologous chromosome pairs align at the metaphase plate, preparing for separation.

Anaphase I

The stage of meiosis where homologous chromosomes are pulled apart to opposite poles, reducing the chromosome number by half.

Telophase I

The stage of meiosis where the cell divides into two haploid cells, each containing half the number of chromosomes.

Cytokinesis in Meiosis I

The process following meiosis I where the cytoplasm divides, resulting in two haploid daughter cells.

Prophase II

The stage of meiosis II where the chromosomes condense again and the nuclear envelope breaks down if it had re-formed.

Metaphase II

The stage of meiosis II where chromosomes align at the metaphase plate, similar to metaphase in mitosis.

Anaphase II

The stage of meiosis II where sister chromatids are separated and pulled to opposite poles of the cell.

Telophase II

The final stage of meiosis where the nuclear envelope re-forms around each set of chromosomes, leading to four haploid cells.

Cytokinesis in Meiosis II

The process that follows meiosis II, resulting in the division of the cytoplasm and the formation of four distinct haploid cells.

Crossing Over

two chromosomes meet (at the chiasma) and exchange genetic material, known as Genetic Recombination.

Haploid cells

a cell containing only one set of chromosomes (23) - gametes

Diploid cells

a cell containing two sets of chromosomes (46) - body cells, zygotes

How does fertilisation initiate mitosis?

By two haploid cells (gametes) fusing to form a diploid cell (zygote) which undergoes mitosis (growth) forming an embryo

How does meiosis split chromosomes

into 4 non-identical daughter chromosomes

How does mitosis split chromosomes

into 2 identical daughter chromosomes

Parts of a flowering plant

Parts of a chromosome

Parts of a cell in every cell

Cell membrane, DNA, Ribosomes

how is self-pollination different to cross-pollination

produces more genetic diversity in plant populations