genetics 1 - the cell cycle Flashcards
What does the cell theory state?
- All living things are made up of one or more cells
- Cells are the smallest units of living organisms
- New cells only come from pre-existing cells by cell division
Where do daughter cells come from
Parent cells
Somatic cells contain twice the number of…
Twice the number of chromosomes as gamete cells
What do gamete cells consist of
Ovum and sperm
How many chromosomes do humans have
46
What is the difference between a haploid and diploid cell?
Haploid cells only consist of one set of chromosomes.
Diploid cells consist of two sets of chromosomes
Somatic cells are diploid. Examples include:
Body (somatic) cells (nerve, muscle, bone)
Gamete cells are haploid. Examples include:
sex cells (sperm & egg)
What are the functions of cell division?
- Growth of Organisms
- Repairing of tissue and/or organs
- Replacing dying/dead cells
(and reproduction, but only for unicellular organisms such as bacteria)
What are chromosomes made up of?
DNA containing genetic information and protein
Chromatins are ___, whereas chromosomes are __
chromatins are long, thread-like, and spread out
whereas chromosomes are tightly condensed
What is a chromatid?
A half of a duplicated chromosome
Before mitosis, DNA replicates to form..
Two genetically identical sister chromatids held together at the centromere
How many chromosomes and chromatids are on this?
xx xx xx ( xx xx (
22 chromatids
12 chromosomes
What is the longest phase of interphase
The G1 phase
What happens in the G1 phase?
Cell growth, development, duplication of organelles, and metabolic activity. Proteins and RNAs are synthesized, and the centromere is made.
Why is the G1 checkpoint important?
It ensures that the cell is large enough to divide and has enough nutrients to support daughter cells, and checks that DNA isn’t damaged
Why are there G (Gap) phases?
Before mitosis occurs, the parent cell has to be large enough in size and have created the required organelles so that daughter cells will operate normally
What happens in the synthesis phase?
Chromosomes are replicated and DNA exists as an uncondensed chromatin (looks like a bowl of spaghetti)
What happens in the G2 Phase?
Growth of cells and the duplication of organelles continues. More metabolic activity going on to prepare for mitosis