germ cell development (lecture 1)

where is the overview for the class?

developmental biology

what we learning in this lecture?

how germ cells develop

what are germ cells and what do they develop into?

germ cells are reproductive cells that develop into sperm and egg.

what are you supposed to know after this lecture?

-germ cells vs somatic cells

-origin of germ cells in different animals

-“Primordial” Germ Cell Development and Migration to the Gonads

Development of Primary and Secondary Sex Organs: A Collaboration of Germ and Somatic Cells

Chromosomal Sex Determination: Role of Sex Chromosomes and the Sry Gene in Mammals

Environmental Sex Determination: Example of Control by Temperature

gonad

an organ that produces gametes; a testis or ovary.

gametes

Gametes are an organism's reproductive cells. They are also referred to as sex cells.

Female gametes are called ova or egg cells, and male gametes are called sperm. Gametes are haploid cells, and each cell carries only one copy of each chromosome.

what are male gametes called?

sperm

what are female gametes called?

eggs/ ovules

Key Differences Between Germ Cells and Somatic Cells (slide 6)

these are facts and are not part of the puzzle

germ cells

reproductive cells that develop into sperm and eggs

somatic cells

any cell of a living organism other than the reproductive cells.

which cells produce the current and next generation?

somatic cells produce the current generation

germ cells product the next generation

in terms of mitosis and meiosis, germ cells and somatic cells undergo which?

germ cells undergo both mitosis and meiosis

somatic cells only undergo mitosis

Meiosis is a specialized cell division process that occurs in sexually reproducing organisms, resulting in the production of gametes (sperm or egg cells)

Mitosis is the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division

which cells, somatic and germ, are haploid and diploid?

Haploid refers to the presence of a single set of chromosomes in an organism's cells. Sexually reproducing organisms are diploid (having two sets of chromosomes, one from each parent).

Germ cells can be 1n (hapoloid) or 2n (diploid), whereas somatic cells are usually 2n (but can be 3n or 4n in some cases)

Germ cells can make more germ cells, which ultimately become male or female gametes in the reproductive organs, or somatic cells. They produce the next generation.

• Somatic cells can only make somatic cells (and not germ cells), which become the cells of differentiated tissues and organs (except germ cells) in the current generation

(slide 7) germ cell development occurs in three stages. what is the first stage?

Developmental Origin in the Previous Generation

this makes sense, because germ cells must first originate

(slide 7) germ cell development occurs in three stages, what is the second stage?

migration to gonads as “primordial” germ cells in the current generation

(slide 7) germ cell development occurs in three stages, what is the third stage?

differentiation into sperm or eggs (sex determination) in the current generation

where does germ cell development occur?

Germ Cell Development occurs in the embryo along with somatic development

what are the two ways that germ cells are able to develop? what is the difference between the two ways?

(part of the puzzle because we are looking at germ cell development in different animals)

Germ cells can develop autonomously (using information from inside the precursor cells themselves) or non-autonomously (using information obtained by signaling from other cells)

what are the two animals that autonomous germ cell development occurs in?

insects and frogs

what is the type of animal that non-autonomous germ cell development occurs in?

mammals

all the small bumps are somatic cells

from the shape of the egg, we can see the anterior pole and the posterior pole

if you have the granules, it becomes a germ cell

if you don’t have the granules, it becomes a somatic cell.

SUMMARY (puzzle built from notebook)

what are the facts you need to know from lecture 1?

-the differences between somatic and germ cells (slide 6) which I already put in the flashcards above

-germ cell development slide that fits into the rest of the puzzle (slide 8)

overview of puzzle

the three stages of germ cell development

1. developmental origin in previous generation

2. migration to gonads as primoradial germ cells in the current generation

3. differentiation in sperm or eggs (sex determination) in current generation

once you reach sperm and eggs, aka sex determination, you have completed germ cell development

WHERE does germ cell DEVELOPMENT occur?

embryo (along with somatic cell development)