CH 9 Cellular reproduction
Why do cells divide?
Cells reproduce by cell division whereby a parent cell produces 2 daughter cells
o Transmission of hereditary information to daughter cells
o Growth & development
o Sexual & asexual reproduction
Prokaryotic fission:
o DNA attached to plasma membrane
o DNA replicates
o New membrane grow between DNA & grows downward
o Parent cell divide: 2 daughter cells
DNA: single strand composed of subunits
↓
Nucleotides: DNA subunits consisting of phosphates, base, sugars
↓
Genes “units of inheritance”: segments of DNA with nucleotides (found on specific locus on
chromosome)
Chromosomes: consists of 2 DNA strands wrapped around each other in double helix
DNA packaged into chromosomes
Centromeres:
Holds 2 daughter DNA double helix together after DNA replication
Attachment site for microtubules that move chromosomes during
cell division
Karyotype: “Complete set of chromosomes from a single cell”
EUKARYOTIC CELL CHROMOSOME PAIRS TOTAL CHROMOSOMES
AUTOSOMES 22 44
, SEX CHROMOSOMES 1 2
DIPLOID = 46 = 2N
Diploid: 2N=46: “Cells with pairs of homologues chromosomes”
Haploid N=23 (22 autosomes & 1 sex): “Cell containing one member of each chromosome”
Autosomes = 22 pairs of homologous chromosomes: “All body chromosomes excluding sex
chromosomes. Pairs of chromosomes with nearly identical DNA sequences found in diploid
cells, both sexes”
Sex chromosomes 2 (XX or XY): “Autosomes, humans, most mammals have 2 sex chromosomes
(XX/XY)”
Homologous chromosomes:
Paired chromosomes, diploid
2 chromosomes that make up a pair containing genes that control
same characteristic
Eukaryotic cell cycle:
Cell phases in replication
1. Interphase (longest phase)
G1 grow and differentiate S DNA synthesis & duplicate chromosomes G2 growth &
division prep
2. Mitosis: body cells 80 mins (start with diploid 2N=46 chromosomes)
Nucleus divide into 2 nuclei
New cells in cytokinesis
1. Interphase
G1 grow and differentiate S DNA synthesis & duplicate chromosomes G2 growth &
division prep
2. Meiosis: germline cells 24 hours (start with diploid 2N=46 chromosomes)
diploid cells go through meiosis producing 4 haploid cells
Diploid meiosis haploid fuse diploid (2 gametes fuse to get embryo)
Meiosis I: 2 unique daughter cells (1/2 DNA of germline parent)
Why do cells divide?
Cells reproduce by cell division whereby a parent cell produces 2 daughter cells
o Transmission of hereditary information to daughter cells
o Growth & development
o Sexual & asexual reproduction
Prokaryotic fission:
o DNA attached to plasma membrane
o DNA replicates
o New membrane grow between DNA & grows downward
o Parent cell divide: 2 daughter cells
DNA: single strand composed of subunits
↓
Nucleotides: DNA subunits consisting of phosphates, base, sugars
↓
Genes “units of inheritance”: segments of DNA with nucleotides (found on specific locus on
chromosome)
Chromosomes: consists of 2 DNA strands wrapped around each other in double helix
DNA packaged into chromosomes
Centromeres:
Holds 2 daughter DNA double helix together after DNA replication
Attachment site for microtubules that move chromosomes during
cell division
Karyotype: “Complete set of chromosomes from a single cell”
EUKARYOTIC CELL CHROMOSOME PAIRS TOTAL CHROMOSOMES
AUTOSOMES 22 44
, SEX CHROMOSOMES 1 2
DIPLOID = 46 = 2N
Diploid: 2N=46: “Cells with pairs of homologues chromosomes”
Haploid N=23 (22 autosomes & 1 sex): “Cell containing one member of each chromosome”
Autosomes = 22 pairs of homologous chromosomes: “All body chromosomes excluding sex
chromosomes. Pairs of chromosomes with nearly identical DNA sequences found in diploid
cells, both sexes”
Sex chromosomes 2 (XX or XY): “Autosomes, humans, most mammals have 2 sex chromosomes
(XX/XY)”
Homologous chromosomes:
Paired chromosomes, diploid
2 chromosomes that make up a pair containing genes that control
same characteristic
Eukaryotic cell cycle:
Cell phases in replication
1. Interphase (longest phase)
G1 grow and differentiate S DNA synthesis & duplicate chromosomes G2 growth &
division prep
2. Mitosis: body cells 80 mins (start with diploid 2N=46 chromosomes)
Nucleus divide into 2 nuclei
New cells in cytokinesis
1. Interphase
G1 grow and differentiate S DNA synthesis & duplicate chromosomes G2 growth &
division prep
2. Meiosis: germline cells 24 hours (start with diploid 2N=46 chromosomes)
diploid cells go through meiosis producing 4 haploid cells
Diploid meiosis haploid fuse diploid (2 gametes fuse to get embryo)
Meiosis I: 2 unique daughter cells (1/2 DNA of germline parent)
