Meiosis process

• - these are paired chromosomes.
• - both these chromosomes carry a pair of “ matching genes” 
•  - homologous = same information
• - they control the same inherited characters 
• - the single stranded chromatids replicate to form two chromosomes.,

• - the 46 chromosomes are divided into 2  cuz 23 chromosomes come from the and the other 23 come form the dad 
• - then when they come together through the process of fertilization to create the 46 chromosomes.

Oogenesis

- spermatogenesis

• It reduces the chromosomes number 
• - makes gamers from diploid to haploid 
• - fertilization restores it to 46 chromosomes making a zygote

• - this is the crossing over of the mom and dad chromosomes known as synapsis.( crossing over ) 
• - the homologous pairs with one from mom and dad swap genes. 
• - They basically swaps pieces of genes  
• -

• - also known as monozygotic 
• - one egg and sperm combine to make a zygote that then splits up to make 2 embryos. 
• - it’s a clone of the zygote

• - dizygotic 
• - 2 eggs and sperm are fertilized at the same time to create 2 embryos with different genetic information.
• - it can boy or girl

• Identical to the parent 
• - 1 parent 
• - faster and less energy 
• - single celled organisms ( fungi, protists , hydra)

• - parthogenesis -  adult forming from unfertilized egg. Clone 
• - binary fusion = mitosis that occurs in bacteria
• - budding 
• - fragmentation- when a part of the plant falls off and something grows 
• -runnus- when the roots are running underneath

• - presence of 3 homologous chromatids in every cell. 
• - zygote contains 47 chromatids not 46 ( and have 3 chromatids instead of 2 ) 
• - Down syndrome  or trisomy 21

• - zygote has 45 chromatids. 
• - basically have only 1 chromatid in a pair 
• - turner syndrome

• -  IMAGE of your chromosomes .
• - helps us find genetic disorders. As well as the biological sex. 
• - like after prophase and during metaphase in mitosis 
• mother= XX
• DAD =XY

Are the 22 chromosomes that are not related to your biological sex

Which is the 23rd pair relates to your biological sex

- genetic variation eg independent assortment, crossing over, random fertilization ( which sperm fertilizes which egg we don’t know )

No meiois is non cyclic and mitosis is cyclic

• - mitosis 
• - somatic cells 
• - cytokinesis done once 
• - duplicate chromosomes once during the s phase 
• - 2 identical diploid cells 
• - they grow and repair, to keep skin cells the same 

• - we produce gametes 
• - cytokeneis done 2 times
• - Dna replicated once in the s phase 
• - 4 gametes which are haploid ( 23 chromosomes)
• - start 46 and end with 43 
• - for reproduction 
• - for diverse babies

- The random alignment of homologous chromosomes in metaphase 1

- Then the homologous pairs move to the centre, metaphase plate while the centrioles move to the opposite end.

- The spindle fibres pull one chromosomes each from the homologous pairs and move it towards the centrioles.

- This is when the chromosmes are now at their poles and a nuclear membrane begins to form and then cytokenisis takes place and we have 2 haploid cells.

• - This is when the the nuclear member decomposes 
• - centrioles begin to move to the opposite poles

- this is when the chromosmes line up in the centre ( metaphase plate)

• - the spindle fibres pull apart the chromosomes resulting in the centromere breaking and chromatids moving towards  the centrioles. 
• - independent assortment 
• -

• - results in 4 haploid cells that are genetically different 
• -

• -This is when the  chromosomes fail to separate correctly. 
• - once a zygote with an abnormal amount of chromosomes begins to replicate EVERY CELL IS AFFECTED. 
• - two homologous chromosomes move to the same pole during anaphase  1 or 2 resulting in one daughter cell having an extra chromosome while  another is missing one