IndietroChapter 5: Cell Division and the continuity of life
Termini in questo insieme (82)
Why do cells divide?
To go from single cell to multicell to person to produce sexual activity
Cell Cycle
In eukaryotic cells, the repetitive pattern of cell growth, DNA synthesis, and division during cells life span
Interphase
In stage where cells grow, replicate their chromosome, and perform their duties.
Cells spend the majority of their time in what?
Interphase
The three phases of interphase
G1, S-Phase, G2
G1
The initial growth after cytokinesis, and grows to a functional size
S-Phase
Synthesis (replication of DNA)
G2
Period of more growth as cells prepare for mitosis and cytokinesis
Mitosis
A method of nuclear division where SUMATIC CELLS produce two identical nuclei and package them into two individual daughter cells
Ploidy
Chromosome Set
Diploid can
2 chromosome sets
Haploid (n)
1 chromosome
Somatic Cells
All cells excluding gametes (sperm and eggs)
Mitosis always produces two what?
Identical nuclei that are diploid
Cytokinesis
Stage of the cell cycle where the cytoplasm of the parent cell splits to form two individual cells after completing mitosis
What is cytokinesis not part of?
Interphase of Mitosis
Chromatin
Thread-like fibers of chromosomes and proteins
Chromatin does what during cell division?
Condenses
What state of chromatin allows cells to have access to their genes?
Unpacked
Chromosome
Condensed, rod like version of DNA
Why does mitosis exist?
To clone nuclei
Gene
A unit of genetic information that tells a cell how to express a trait
The four distinct stages of Mitosis
PMAT
Each stage of PMAT is?
Prophase, Metaphase, Anaphase, Telophase
Prophase
Removes the nucleus by getting rod of the nuclear membrance
What do chromosomes do during prophase?
Become visible and able to tell the difference between them
Whats mitosis seemingly choreographed to do during prophase?
Ensure equal distribution of DNA
What disappears in prophase?
Nuclear envelope and the Nucleolus
Chromatin condenses into what during prophase?
Chromosomes
What comes into formation during prophase?
The centrosome
Replicated chromosomes are composed of what?
Two sister chromatids
What is joined at the centromere?
Sister chromatids
Centrosome
The region of a cell that produces the miotic spindle
Metaphase
Replicated chromosomes are aligned at the metaphase plate
What completes during metaphase?
The mitotic spindle
Anaphase
Separation of the sister chromatids by contractions of the mitotic spindle
Each chromosome set does what in anaphase?
Migrates to the opposite poles
Telophase
Exact opposite of prophase
What becomes reconstructed during telophaae?
The nucleus and nuclei
Chromosomes become what during telophase?
Chromatin and impossible to tell apart
What happens at the end of telophase?
Two cells will be equal to 6 chromosomes
What breaks down during telophase?
The spindle apparatus
What reappears during telophase?
The nuclear envelope and the nucleolus
Cytokinesis
The cytoplasm is divided and produces two daughter cells
Cancer
A condition where cells have escaped the control of cell division
Whats out of control in cancer?
Cell growth and mitosis
Carcinogens
Substances that transform normal cells into cancer cells
Cancer cells
Cause mutations that enable cells to evade checkpoints controlling mitosis
What mutations occur in cancer cells?
Too much sunlight, viruses, chemicals
At high populations, cells stop dividing due to:
Limited growth factors, Limited Nutrients, and substrate for anchorage
Contact inhibition
The tendency of cells to lay side by side and stopping division when they are touching neighboring cells
Benign tumor
Cells that have lost control kf mitosis but remain in place and do not invade adjacent tissues
What may not cause serious problems and can be treated with surgery
Benign tumor
Malignant tumor
Cancer cells that invade adjacent tissues
What can interfere with the function of one or more organs, and can also be treated with surgery, chemo, and/or radiation?
Malignant tumor
Chemotherapy does what?
Destroys cancer cells, but other cells too.
Metastasis
Cancer that spreads throughout the body, many organs becoming infected
What are our species cells?
Diploid
What is very careful to maintain the chromosomes in a cell?
Mitosis
Meiosis followed by two rounds of cytokinesis
Always produces 4 genetically unique nuclei
How is meiosis different than mitosis?
Meiosis always produces haploid(n) cells
Haploid
Cells that contain one set of chromasomes
Mitosis in humans always produces what type of cells?
Diploid (2n)
Diploid
Cells that contain two sets sex of chromosomes (one set from each parent)
What occurs in sex organs?
Diploid cells
Zygote
Divides by mitosis into a fetus
What has 46 chromosomes, 22 pairs of autonomous, 44 chromosome, 2 sex chromosome
Zygote
The fetus divides into an infact how?
Mitosis
Mitosis produces a what?
Sexual reproductive adult
Sex organs convert diploid cells into haploid sex cells by how?
Meiosis
Sex cells contain what?
22 autosome and 1 sex chromosome
Interphase
Chromosomes are replicated
What phase is interphase?
Prophase 1
Homologous chromosomes
Pair in process called synopsis
What chromosomes are the same function, shape, and size; thus they contain the same genes?
Homologous
What may occur with genetic material when homologous chromosomes intertwined during prophase 1?
Crossing over
Metaphase 1
Homologous chromosomes move and align on the metaphase plate
Independent assortment
Random alignment of homologous chromosomes on the metaphase plate of metaphase 1
Anaphase 1
Homologous chromosomes split to produce replicated chromosomes composed of sister chromatids
Homologs move to what?
Opposite poles
Whats the objective of meiosis?
To turn diploid cells into haploid cells, and to separate homologous chromosomes.
Whats the overall goal of meiosis 2?
To separate chromatids