16.1 The Cell Cycle Flashcards
Why must a cell stop growing once it meets a certain size?
Because the cytoplasm grows at a faster rate than the cell membrane. So the cell membrane would not be able to meet the needs of the cell
What is spontaneous generation?
The theory that living organisms could arise from non-living matter
Who was the first scientist to determine to propose an alternative to spontaneous generation?
Rudolph Virchow
What did Rudolph Virchow propose?
That new cells only arise from the division of other cells
What is the Cell Cycle?
The life cycle of the cell
What are somatic cells?
Body Cells
What does the variation of the life cycle of a somatic cell depend on?
Their type and environment
Which of the body cells are replaced frequently?
Blood cells and skin cells
Which of the body cells are not replaced frequently?
Nerve Cells. Some don’t even divide
What does the cell cycle of Somatic cells consist of?
A period of cell maintenance where the cell seems to be resting and a period where it divides
What is a single cell cycle defined as?
The sequence of events from one cell cycle to another
Why couldn’t scientists decifer how the division of cells work?
Because genetic material under the microscope appeared clear and they could not see specific structures
How were scientists able to isolate certain structures of cells?
By using clothing dye
Who came up with the method to use clothing dye?
Walter Flemming
What is the structure and function of a cell determined by?
Its genetic material
What is the central feature of the Cell Cycle?
The way genetic material is duplicated and passed from the parent cell to each new daughter cell
Where is the genetic information of a cell contained in?
Its DNA
What is DNA?
A molecule of nucleic acid that governs processes of heredity in the cells
Where is DNA found?
In each chromosome of a cell
What is chromosome?
A length of DNA and its associated proteins
Where are chromosomes found in eukaryotic cells?
In the nucleus
What are Eukaryotic cells?
The cells that make up Protists, Fungi, Plants and animals
What compacts all the DNA within a cell?
Highly specialized proteins known as Histones
What does the genetic material appear as during most of the cells life?
A mass of long intertwined strands known as chromatin
What happens that causes the Chromatin to be visible?
The process of cellular division that causes the Chromatin to condense and be visible as distinct chromosomes
What is the centromere?
The pinched in region in a condensed chromosome
What is the organization of DNA?
First DNA molecules wind around Histones to form bead like structures. The bead like structure forms tightly packed arrays to produce strands of chromatin. Chromatin fibres form loops which are attached to a supporting protein scaffold. The scaffold further condense the genetic material into chromosomes
What can the chromosomes be organized into?
22 pairs of homologous chromosomes known as autosomes
What are Autosomes?
The 22 pairs of homologous chromosomes within a cell
What is the last pair of cells not included with the Autosomes?
2 sex hormones that may or may not be a homologous pair
What is a Homologous pair?
2 similar looking chromosomes
What are the sex chromosomes called?
X and Y
What are the labels of the Sex chromosomes if a person is female?
XX
What are genes?
Areas of DNA that contain specific information?
What do homologous chromosomes contain?
The same genes at the same location or locus
What makes homologous pairs different from each other?
They carry different forms of the same gene (alleles)
What are Alleles?
Different forms of the same gene
What is a Diploid?
A cell that contains pairs of homologous chromosomes
What is the Diploid numbers in humans?
46 or 23 pairs
What is a Haploid cell?
A cell that contains unpaired chromosomes
What cells in the body are Haploid cells?
Human gametes
What is the Haploid number of cells in humans?
23
What is Polyploid?
When an organism has sets of more than two homologous chromosomes
How do Autosomes 1 to 22 differ from each other?
They vary in overall length, location of their centromere and their staining property. But these characteristics are the same in Homologous pairs
What is an individual’s Karyotype?
The particular set of chromosomes that an individual possess
How do scientists prepare a karyotype?
Scientists collect a cell sample and use chemicals to stop the cell cycle when the chromosomes are most clearly visible then they stain them to help identify individual chromosomes
What is the growth phase of a cell cycle called?
The interphase
What happens during the interphase?
The cell carries out regular metabolic functions and prepares for its next division
What are the 3 phases of the Interphase?
G1, S, G2
What happens during the G1 phase?
The stage where the cell grows quickly
What happens during the S Phase?
The DNA in chromatin replicates to create a second set of identical DNA
What are Sister Chromatids?
During the S phase when the DNA in chromatin is copied and the chromatids are joined at the centromere
Why is the S phase known as the S phase?
Because the S is known as Synthesis where the DNA is replicated
What is the G2 phase?
Where the cell rebuilds its reserves of energy for the division since the duplication of DNA has consumed a great deal of energy
What ends the Interphase?
Mitosis
What are the 2 main processes in cell division?
Mitosis and Cytokinesis
What is Mitosis?
The division of the genetic material and the contents of the nucleus into two complete and seperate sets
What is Cytokinesis?
The division of the cytoplasm and organelles into two seperate cells
