Perkembangan sel telur

Spermatogenesis terjadi melalui beberapa fase , yaitu :

a. Fase Pertumbuhan

b. Fase Pembelahan

c. Fase Diferensiasi

1. Fase Pertumbuhan

MITOSIS DAN MEIOSIS

SIKLUS SEL

•          G1(gap 1): periode setelah mitosis, gen-gen aktif berekspresi

•          S (sintesis): fase sintesis DNA (replikasi), kromosom ® dua kromatid

•          G2 (gap 2): setelah S, terjadi aktifitas gen-gen untuk mengontrol pembentukan protein/ enzim untuk keperluan mitosis

•          G0: fase istirahat, dormant (contoh: sel otot, sel darah merah)

Dalam kultur sel tertentu, G1: 16-24 jam, M: 1-2 jam. Terdapat variasi yang besar dalam lamanya siklus sel

MITOSIS

•          Pembelahan sel somatis ® 2 anak sel yang mengandung jumlah kromosom/ materi hereditas yang sama atau identik.

•          Tujuan:

1. Mengganti sel-sel yang rusak/ regenerasi
2. Perkembangan dari satu sel menjadi banyak
3. Membentuk individu baru (reproduksi sel baru) pada individu bersel tunggal

Secara umum, pembelahan sel terbagi menjadi 2 tahap, yaitu: Kariokinesis dan sitokinesis

KARIOKINESIS

Profase:

•          Membran inti mulai hilang

•          Nukleolus (anak inti) mulai hilang

•          Kromosom terlihat tebal dan panjang (terdiri dari 2 kromatid)

•          Di sitoplasma terdapat sentriol yang membelah menjadi 2 dan bergerak ke arah kutub yang berlawanan, terbentuk benang spindel (mikrotubul)

Games-based learning

Games-based learning is one of the latest ideas to improve the schooling experience for a large number of 8 to 10 year olds. The children who first participated in games-based learning attend a small primary school on an
island in the middle of the Atlantic. The idea was the brain-child of teacher Rodriguez Desai who wanted the children he was teaching to improve their ability to learn in a more relaxed way. He also wanted them to have the opportunity to socialise with pupils from other schools. He noticed that, in the early 1990s, boys in particular brought hand-held games consoles into school as part of the end of term activities. These boys were not very highly motivated in class and were thought to be of lower than average ability. When Rodriguez began to watch these 'failing' boys he was amazed. He realised that the skills needed to play these hand-held games included high-level, intelligent reasoning.

The boys had to analyse situations, develop strategies for dealing with the
problems, solve the problems and work with one another to gain the best outcome. Rodriguez began
to understand that learning to play computer games could actually benefit all kinds of learners. He
started to think about the best ways he could use them to teach pupils who were not normally keen
on traditional school work.

Dolphin

Humans have always been fascinated by dolphins and there has been a long history of association

between the two. Over time this has turned into a rapidly expanding world-wide tourist activity –

swimming with dolphins. The chance to see dolphins in the wild is often a lifetime dream for many

people, but few consider the implications of actually swimming with these animals.

The ‘swim-with-dolphins’ tourist industry is becoming more popular every year and tour operators are

always on the lookout to give their tourist swimmers the best experience they can. After all, it can cost

a large amount of money to have this kind of holiday experience. So tour operators try to place eager

swimmers as near as possible to the dolphins by trying to predict where the dolphins will be. The

swimmers usually enter the water from the back of a stationary boat and swim freely in the water.

Research has shown that while dolphins can move away if they do not want to interact with human

swimmers, they do not like it at all if the swimmers slip into the water directly on top of them or if

humans are in their path of travel. However, if swimmers enter the water to one side of them, the

dolphins do not avoid the swimmers to the same extent. This possibly seems like less threatening

behaviour to them.