Skeletal structure and function
Description

Skeletons support and protect our bodies. Bugs have exoskeletons outside their bodies, while humans have endoskeletons inside. Our bones are in axial (skull, ribcage, spine) and appendicular (arms, legs) groups. Bone marrow makes blood cells; more specifically, red marrow makes blood and yellow marrow stores fat. 

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Tracy Kim Kovach
Antiparallel structure of DNA strands
Description

DNA is made up of two strands. Each strand has a backbone made up of alternating sugars and phosphate groups. The two strands are linked by complementary nitrogenous bases. The strands are oriented in opposite directions, making the structure "antiparallel".

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Human fertilisation and early development
Description

Overview of fertilisation and early human development. From conception leading to a zygote to blastocyst, embryo and fetus.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Comparing mitosis and meiosis
Description

Comparison of the processes of mitosis and meiosis. Mitosis produces two diploid (2n) somatic cells that are genetically identical to each other and the original parent cell, whereas meiosis produces four haploid (n) gametes that are genetically unique from each other and the original parent (germ) cell. Mitosis involves one cell division, whereas meiosis involves two cell divisions.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Phases of meiosis II
Description

Meiosis is a process that creates sex cells (gametes) with half the number of chromosomes of the parent cell. Meiosis has two stages: meiosis I and meiosis II. In meiosis I, homologous chromosomes pair up and exchange genetic material (crossing over). In meiosis II, sister chromatids separate, creating four haploid cells.

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan
Chromosomal crossover in meiosis I
Description

Meiosis is a process where germ cells divide to produce gametes, such as sperm and egg cells. In prophase I of meiosis, chromosomes condense and homologous recombination takes place, leading to genetic variation through chromosomal crossover. This forms a tetrad, which is made up of four chromatids (two sister chromatids per chromosome).

Language
English
Resource Type
Publisher
Khan Academy
Publication Date
Creator/Author
Sal Khan