cell cycle , mitosis , meiosis Flashcards
—- the process by which cells copy their dna and divide to produce genetically identical daughter cells
cell cycle ( G0 , G1 , S , G2 )
G0 is an — non-replicative phase and many differentiated cells remain in their such as —
- optional
- hepatocytes
is a phase where cellular contents excluding the chromosomes duplicate , the preparation of cell division as well as the period of cell growth is —-
G1 phase ( 10 hours )
true or false:
the G1 phase also includes replication of key components such as centrosomes
true
The S phase in known as — where — occurs and it takes — where each of the 46 chromosomes id duplicated by the cell
- synthesis
- dna replication
- 5-6 hours
a short resting phase as the cell double checks the duplicated chromosomes error and making any needed repairs before cell division which takes 3-5 hours is known as —
G2 phase
humans have – chromosomes pair homologs which is — from autosomes and — from sex chromosomes . The sex determining chromosomes are — for females - and —- for male
- 23 ( 2n ) , 22 autosomes + sex chromosomes
- XX
- XY
cell division is required for —– and to — new cells in adults
- development
- generate
in somatic cells the division occurs in — during the cell cycle and it produces — cells aka — chromosesm
- mitosis
- diploid
- 2n , 2 copies of chromosomes
— refers to the cell division and takes 2 hours
mitosis
to generate gametes we need —- which is the specialised form of cell division and produces gametes ( sperm and eggs ) in — which is – copy
- meiosis
- haploid
- one copy , n
true or false:
genomic dna must be copied accurately and divided between the daughter cells
true
in — the dna is copied once so we have 46 chromosomes made of 2 chromatids held together by —- , they separate to form — chromosomes before divide once and become —-
- mitosis
- centromere
- 92 chromosomes
- 92/2 cells = 46 chromosomes which means = 2 x 23 diploid
in G1, S , and G2 the —- is intact and — is not visible
- nuclear envelop
- chromosomes
—- is a process when chromosomes are visible as the chromosomes consist of 2 sister chromatids , miotic spindle forms and nuclear membrane breaks
prophase
sister chromatid line up at the centre during —-
metaphase
sister chromatids are pulled apart and move to the opposite ends during —
anaphase
spindle fiber break down , nuclear membrane forms , the chromosome begin to uncoil and forms chromatin
telophase
the break down into 2 of cytoplasm and the cell divide is called —-
cytokineses
— phase is when the nucleas break apart an attach to kinetochore
prometaohase
the microtubule organising centre seeds outward growth of polar fiber is —
centresome
—- is an essential dna sequence for the segregation of during cell division ( the lack of eccentric centromere don’t attach to the spindle , not passed to the daughter cells )
centromer I ( check slide 11 for the structure )
— pattern of cell division that produces gametes aka germ cells ( eggs and sperm ) which are — and contain – copies of chromosome and the dna is copied —-
- meiosis
- haploid
- one copy
- once
( 46 chromosomes made of 2 chromatids held together in the centre of centromere ) so ,
46/2 chromatids , 23/2 chromatid , 23/single chromatid = 92/4 = 23/cell haploid
in meiosis the chromosomes condense as the nuclear envelop break and the crossing over ( aka exchanging segment ) occurs —
prophase 1
when the chromosomes duplicate —
interphase
pairs of homologous chromosomes move to the centre and the microtubule is attached to the kinetochore in —
metaphase 1
homologous chromosomes move to the opposite poles as they split up in —-
anaphase 1
the chromosomes gather at the pole and the cytoplasm divides , 2 haploid cells form and the chromosomes are still double in
telophase and cytokines
- a new spindle forms around the chromosomes in —-
- the chromosomes line up the equator in —-
- centromeres divide and chromatid move to the opposite poles of the cells and sister chromatids separate in —-
- a new nuclear envelop forms and cytoplasm divides , haploid daughter cells forming
- prophase 2
- metaphase 2
- anaphase 2
- telophase 2
true or false:
during mitosis another round of cell division as the sister chromatid finally separates , 4 haploid cells form containing single chromosomes , division without replication
false , mieosis
genetic diversity is generated in meiosis by 2 process —–
1-recombination ( pachytene in meiosis I )
2- independent assortment
— refers to the physical breakage of dna duplex in one maternal and one paternal chromatids and joining of the end.
recombination
in recombination the dna sequence is exchanged between — but the dna sequence is —-
- chromatids
- neither gained not lost unless a mistake as: non-disjuction = cytogenetics
recmombination doesnt normally occur in —- but once that happens the dna sequence is ——
- mitosis
- gained or lost leading to bad results
—- is when each bivalent is a 4 stranded structure ( 4 chromatids ) and the mitotic spindle pulls 2 chromatids towards each pole
independent assortment
true or false: for humans
2 power 23 = 8.4 x 10 power 6 possible combination
true , check slide 16 + 17
— identical copy of maternal and paternal homolog
— mixed copy of maternal or paternal homolog
- diploid
- haploid
1-mitotic tetrads with — chiasmata
2- each chiasmata marks a —-
3- on average — chismata/cell in human make meiosis up to — more in females
- 2
- crossing over point
- 55
- 50%
— is important for correct chromosome segregation at meiosis I , holds the homologs together until align along plate and formation of spindle until —– . Children w/ incorrect chromosomes number often the product of gametes where bivalent lacked —- . These crossovers may involve — or — in a bivalent
- chiasmata
- anaphase I
- crossover
- 3 or even all chromatids
1-haploid gametes arise by — from a —–
2- in fertilization an egg and sperm chromosomes combine forming —- , further round of —- and —- to form a whole organism
- meiosis
- diploid precursor
- diploid zygot
- mitosis and differentiation
the ——– develops by repeated mitotic divisions of diploid cells leading to the production of —— and —– which then undergo —-
- germ-line
- primary oocytes and primary spermocytes
- meiosis
in ovary the priamry oocytes form in —- but arrest at — of the —– until puberty
- fatal life
- prophase of mieosis 1
true or false:
before puberty one oocyte/month completes meiosis
true or false:
sperm produced continuously from puberty
1- false: after puberty
2- true
most cells are — which means 2 homologs pairs of each chromosomes one — and one — so 2 copies of each gene per —- copy
- diplpoid
- paternal and one maternal
- per one chromosome copy
each gene copy is called an —- as they can slightly vary in their dna sequence so, a person can have a different allele of a — as A , a
- allel
- gene
—- is when a populations of genes have many alleles
polymorphism
different alleles combine to form —-
different genotype ( genetic constitution )
read:
Human inherited diseases
Caused by genetic (ie: DNA) defects
disease genotype — > disease phenotype
Two broad categories:
1. Single-gene (monogenic) defects
Single disease allele, dominant or recessive
Simple Mendelian inheritance pattern
Autosomal dominant
Autosomal recessive
X - linked dominant
X - linked recessive
Identified in families by ‘Pedigree Analysis’
2. Multi-gene (polygenic) defects
Interactions of several genes
Complex (ie: non-Mendelian) inheritance
