Meoisis And Mitosis Flashcards
What is the one characteristic that distinguishes the living from the non-living?
The ability to produce more of their own kind
What are 3 important roles of cell division?
Division of one prokaryotic cell and unicellular eukaryotic cell reproduces an entire organism and it enables a multicellular eukaryote to develop from a single cell
What is a genome?
All of a cell’s genetic information
What is a prokaryote in terms of chromosome?
Single, circular chromosome
What is a eukaryote in terms of chromosome?
More than one linear chromesone
How is DNA organized?
In chromosomes
What is the shape of DNA like?
Double helix molecule wrapped around histone proteins like thread on spools
What is a chromatin?
DNA- protein complex
How is the chromatin organize?
Into long thin fibers that are condensed further during mitosis
How many chromosomes do humans have?
46 chromosomes with 23 pairs
How many chromosomes do all stomatic cells have?
46
How do stomatic cells divide?
By mitosis
What kind of - Oid do stomatic cells have?
Diploid with 2 of each type of chromosome
What kind of cells are gametes?
Sex cells eg.sperm and egg
What kind of - Oid do gametes have?
Haploid with one of each type of chromosome
How do gametes divide?
By meiosis
How many gametes do humans have?
23
What are the phases of the cell cycle? (main)
Interphase, miotic phase and cytokinese phase
What is the G0 phase?
Some cells don’t enter g1 phase after cell division like mature cardiac cells and neurons
What happens in the gl phase?
Cells grow by producing proteins and organelles and some repair is done here
What happens in the gl checkpoint?
Used to determine if the Cell is ready to enter the s-phase and if DNA synthesis can begin
How long does the s-phase for last?
6 hours
What happens in the s-phase?
DNA is replicated here and two copies of DNA molecules are attached at the centromere
What is the longest phase of the cell cycle?
S- phase
What happens at the g2 phase?
Production and movement of cells to proper locations
What happens at the end of the g2 phase? (products basically)
Chromosomes, organelles and cytoplasm are doubled
What happens at the g2 checkpoint?
Checking to maintain DNA stability and if DNA synthesis has been done correctly
What is mitosis?
Division of the nucleus
What happens in the prophase of mitosis? (1st)
Chromosomes are shortening and thickening and grouped into sister chromatids connected by a centromere
In what stage of mitosis does the middle spindle begin to form?
Pro phase/1st
What happens in the metaphase of mitosis? (2)
Spindle fibers move chromes ones to cell center, and centro meres line up at the metaphase plate
What happens at the metaphase checkpoint? (cc)
Checks if tension from two poles are equal and ensures proper segregation of chromosomes
What happens in anaphase in mitosis?
Sister chromatids get pulled and moved to opposite poles which move further apart as polar microtybules lengthen
What do motor proteins de?
Pull chromosomes apart
What happens in the telephase (4) of mitosis?
Chromosomes reach opposite poles, beginning to condense , daughter nuclei and nucleioli form, nuclear envelope reappears and spindle fibers disperse
What happens when cytokinese begins for animals?
A cleavage furrow forms at metaphase plate and splits into two like tightening a draw string
What happens in Cytokinese for plants?
A cell plate forms
What are the 3 major checkpoints of the cell cycle?
G1/s-phase ,’g2/m and the spindle checkpoints
What happens at the spindle check-point?
Checks if all chromosomes are. attached to the spindle and if sister chromatids can separate properly
What are autosomes?
22 pairs of chromosomes that don’t determine sex
What are the sex chromesones?
X and y
How are chromosomes inherited in a pair of homologous chromesones?
One is inherited from the male parent and the other from the female parent
What is the genetic locus?
The location of a particular gene on a chromosome
What does each genetic locus have?
2 alleles with one each homologous chromesone
What dees meiosis involve, in terms of Cell division?
It involves 2 cell divisions, resulting in 4 cells with half normal genetic information
What are non-sister chromatids?
Homologs that contain DNA that codes for same genes but different versions of them
What is the first division of meiosis?
Meiosis 1
What happens in the interphase of meiosis? (1st)
Chromosomes are replicated
What happens in prophase 1 of meiosis? (2nd)
Here synopsis homologous chromosomes pair up
What are tetrads?
4 sister chromoticls crossing over at the chiasmata
What happens in metaphase 1?
Tetras line up and independent assortment occurs and chromosomes separate randomly causing genetic recombination
What happens in anaphase 1? (4th)
Pairs of homologous chromosomes separate with sister chromatids attached by centromere
What is the difference between the anaphase in meiosis and mitosis?
The centromere doesn’t break due to the sister chromatids getting pulled apart in meiosis
What are 3 differences between meiosis and mitosis?
Pairing of homologous chromosomes happens in meiosis but not mitosis, centromere division occurs in anaphase for mitosis and anaphase 2 for meiosis and crossing over of homologous chromosomes happens in meiosis but hot mitosis
What is non disjunction?
When chromosomes fail to separate properly
