dna replication & cell cycle. preparing and dividing the dna each chromosome consists of two...
TRANSCRIPT
![Page 1: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/1.jpg)
DNA Replication & Cell Cycle
![Page 2: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/2.jpg)
Preparing and Dividing the DNA
Each chromosome consists of two identical chromatids, joined by a centromere
In human mitosis, 46 chromosomes form 92 sister chromatids
Each chromatid splits from sister and enters one of the two daughter cells
Now it is considered to be a single chromosome.
chromosomes have telomeres (protective end caps)
With every DNA replication, the telomeres on its DNA become shorter.
No replication if telomeres are too short.
DNA replication must occur before a cell can do cell divisionThe chromatin shorten and thicken into chromatids
Dividing the DNA
![Page 3: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/3.jpg)
DNAdouble helix shapetwo nucleotide
strandsthey run anti-
parallel to each other (in opposite directions)
held together by 2 types of bonds
![Page 4: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/4.jpg)
DNA Bonding1. phosphodiester bonds
- link the phosphate of one nucleotide to the sugar of the other to create the sides
2. hydrogen bonds – connect the complimentary nitrogen bases to create the rungs
![Page 5: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/5.jpg)
DNA Replication“copying of DNA’semi-conservative - each
new DNA strand formed is half an old strand and half a new strand.
![Page 6: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/6.jpg)
DNA ReplicationSteps:1. DNA strand is pulled
apart by the enzyme DNA helicase.
2. DNA polmerase (enzyme), adds nucleotides to each strand which produces two new, identical DNA strands.
3. The strands wrap back up and the cell is ready to divide (mitosis!!!)
![Page 7: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/7.jpg)
The Cell CycleDuring the cell cycle, the cell lives, grows, duplicates its DNA, prepares for celldivision, and then divides into two daughter cells.
The cell cycle
![Page 8: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/8.jpg)
The Cell Cycle Eukaryotic cells go through a growing stage and a division
stage.1. Interphase – growing stage
Regular cell activities take up 90 percent of the cell cycle increases protein supply creates new organelles grows larger 3 parts:G1 & G2 – gap phase, either side
of S phaseS – synthesis phase, DNA is
replicated
![Page 9: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/9.jpg)
2. Mitosis – M phase 2 processes: mitosis and cytokinesis.
1. mitosis - nucleus and genetic material duplicated and distributed equally between two daughter cells (PMAT).
a) Prophase: sister chromatids visible centrioles move to either side of cell spindle fibres attach to chromatids nuclear envelope breaks down
![Page 10: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/10.jpg)
b) Metaphase
chromatids attached to spindle fibres
lined up across centre of cell
![Page 11: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/11.jpg)
c) Anaphase
• chromatids separate from sisters to become single chromosomes
• spindle fibres pull chromo to opposite ends of cell
![Page 12: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/12.jpg)
d) Telophase
chromosomes begin to uncoil and form chromatin
spindle fibers disappear
nuclear envelopes reappear around daughter chromosomes
![Page 13: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/13.jpg)
![Page 14: DNA Replication & Cell Cycle. Preparing and Dividing the DNA Each chromosome consists of two identical chromatids, joined by a centromere In human mitosis,](https://reader035.vdocuments.us/reader035/viewer/2022062309/5697bf721a28abf838c7e8a1/html5/thumbnails/14.jpg)
2. Cytokinesisin animals occurs along the cleavage furrow in plants, occurs along a cell plate (more rigid).two genetically identical daughter cells are produced.Each has a single nucleus, correct amount of DNA,
cytoplasm and organelles, and a plasma membrane.
Daughter cells
Cytokinesis