LESSON 6 Flashcards
in mitosis, Daughter cells are genetically ______ to parent cell – same kind and number of ______
identical ; chromosomes
Mitosis occurs in ____ or body cells
somatic
This is called its _____ number or the total number of chromosomes in a somatic cell.
diploid
Diploid means “_____” and is written as “2N”.
2 sets
the process in which the number of chromosomes in the original cell is reduced by HALF through the separation of homologous chromosomes
meiosis
meiosis is the process in which the number of chromosomes in the original cell is reduced by ____ through the separation of _____ chromosomes
HALF ; homologous
Meiosis occurs in _______ only
sex organs
Males (___) – sex organs are the ___ in humans
Females (___) – sex organs are the ___ in humans
XY - testes
XX - ovaries
Meiosis produces ___ cells – cells with ___ the number of chromosomes as the original cell
sex ; ½
Males – meiosis produces _____
Females – meiosis produces ______
4 sperm ; 1 (viable) egg
Females – meiosis produces 1 (viable) egg
The other 3 cells are called ______ – they give up their _____ to nourish the 1 good egg.
polar bodies ; cytoplasm
Egg and sperm (sex cells) are also called _____
gametes
Gametes have ½ the number of chromosomes as somatic (body) cells. We call this the haploid number. Haploid means “____” and is written as “N”.
1 set
If human diploid number is 46, what is its haploid number? ____
23
*When does meiosis occur in humans?
1.Males beginning at _____
2.Females ______ – all eggs are produced before birth and at puberty eggs mature
puberty ; before birth
Nuclear membrane and nucleolus disappear
prophase 1
Each chromosome is composed of two sister chromatids held together by a centromere and is called _____.
dyad
Crossing over takes place between two non- sister chromatids
prophase 1