BIOL 1203 Week 11: Human Genetics

Gene

A sequence of DNA in a specific location in the genome that encodes for a protein. Arranged on chromosomes in nucleus

Genome

The total genetic content in an organism

Chromatin

A mixture made of DNA and proteins (histones) that packages DNA strands into a compact structure

Chromatid

One half of a duplicated chromosome

Sister chromatids

Two halves of a duplicated chromosome

What do chromatids condense into?

They condense into chromosomes

Central Dogma of Life

DNA →(transcription)→ RNA →(translation)→ proteins

Genetic code

A triplet of nucleotides that code for specific amino acids. E.g. AUA, GCU, GCC

How many chromosomes in somatic (body) cells

46 chromosomes → 23 pairs, with 23 chromosomes from mother and 23 from father

Autosome

Any chromosome that is not a sex chromosome

Sex chromosomes

Females → XX, Males → X Y

Karyotype

A complete profile of a person’s chromosomes. Matched using centromere location, size, and banding pattern

Meiosis

Cell division that creates four unique sex cells, reducing the chromosome number by 46 to 23

Mitosis

Cell division that creates two identical daughter cells

Diploid cell

A cell containing 2 sets of chromosomes (2n)

Haploid cell

A cell containing 1 set of chromosomes (n)

What holds together duplicated chromatids?

Centromeres hold them together

Zygote

The very first cell formed when a female egg and male sperm join during fertilization

4 phases of mitosis (PMAT)

Prophase → Metaphase → Anaphase → Telophase

Events of prophase (mitosis)

1. Chromatin condenses into chromosomes

2. A mitotic spindle forms

3. The nuclear envelope breaks down

Events of metaphase (mitosis)

The chromosomes align at the metaphase plate/middle

Events of anaphase (mitosis)

1. The centromeres split

2. Each member of a chromatid pair moves to opposite sides of the cell

Events of telophase (mitosis)

1. Chromosomes revert back to chromatin form

2. Nuclear envelope forms around each chromatin mass

3. Mitotic spindle breaks

4. Cytokinesis follows

Cytokinesis

Division of cytoplasm