(Summary) Brooks Biological Principles Exam 3 Latest 2024 Solved 100%.
Mitosis
• the duplication and division of the nucleus
• results in clones with no variation or adaptation
• takes place in somatic cells (non-sex cells)
• starts with one cell and creates 2 identical daughter cell...
(Summary) Brooks Biological Principles
Exam 3 Latest 2024 Solved 100%.
Mitosis
• the duplication and division of the nucleus
• results in clones with no variation or adaptation
• takes place in somatic cells (non-sex cells)
• starts with one cell and creates 2 identical daughter cells
• replicated chromosomes are evenly divided so that each daughter cell receives a
complete set (46 chromosomes)
• can occur by itself, but usually involves cytokinesis
• not synonymous with cellular division
• single-celled prokaryotes and single celled eukaryotes reproduce asexually, but
eukaryotes are followed by cytokinesis
Purpose of Mitosis
1. Growth: to increase the number of cells
2. Tissue repair/replacement
3. Asexual Reproduction
Cell Division
A process by which a parent cell duplicates its genetic material and then divides into
two similar cells
= Cytokinesis
Cytokinesis
• the duplication and divison of the rest of the cell, excluding the nucleus
• occurs during telophase
• can happen during mitosis, but generally doesn't have to occur with mitosis
• will either develop into new cell walls (plants) or plasma membranes (animals) for each
daughter cell
Mitosis is not equal to
Cell division/Cytokinesis
Only duplicates the nucleus, not the entire cell
In the cells of some organisms, mitosis occurs without cytokinesis. This will
result in
cells with more than one nucleus (plasmodium/slime mold)
Ploidy
number of the kinds of chromosomes found in a species
denoted as "n"
What is the ploidy for humans?
diploid, 23 pairs of chromosomes, 46 chromosomes total
What is the ploidy for bacteria?
diploid, 46 chromosomes
Haploid (n)
,1 set of each kind of chromosome
no homologous chromosomes
only in gametes
Diploid (2n)
2 sets of each kind of chromosome, one set inherited from each parent
contains a pair of homologous chromosomes
in all other body cells
You should do a ploidy count when
the mitotic or meiotic stages have been completed, and new nuclear membranes
separated into the sets of DNA
Most cells in the body are
diploid
Mitosis
takes any ploidy condition and makes exact copies of that condition
Meiosis
is not versatile (must have a diploid cell) to yield a haploid cell
Germinal Cells
Cells involved directly in the process of reproduction, like testes and ovaries
Somatic Cells
•body cells that are not specialized for reproduction
Ex: muscle and skin
•can't undergo meiosis
•human cells have 46 chromosomes in their somatic cells (contain two sets of
chromosomes known as homologous pairs they are not identical, but they have
similar, specialized characteristics)
Homologous Chromosome Pairs
Refers to pairs of the same kind of chromosome
organized by having the same size that contain genes for the same traits
They are diploid
23 pairs of homologous chromosomes in humans
Locus
Location of the genes in homologues
How many different ways can homologous chromosomes line up?
over 8 million ways
Karyotyping
visual representation of chromosomes by length, size, & centromeres in the same
position pairing up
chromosome 23 determines sex
chromosome 21 most likely to duplicate
useful because you can count the number of chromosomes present
Which chromosome has the tendency to have an extra?
21, less likely to separate due to nondisjunction
Down Syndrome
Problem with Chromosome 21
Does not separate like it should (Trisomy 21)
Autosomal chromosomes
, Chromosomes 1 to 22 in humans
Cell Cycle
•Before mitosis begins, the cell must first grow and duplicate chromosomes
during interphase; cells go through four stages during cell reproduction
•Once this cycle is complete the cell will either undergo mitosis or meiosis
Interphase
known as "resting phase"
•majority of the cell's life is spent in this phase
•occurs between mitotic events, not the first stage of mitosis
•it is a stage of the cell cycle where the cell grows and genetic material is copied
•main metabolic events occur: photosynthesis & cellular respiration
•DNA is fully functional during interphase
3 Stages of Interphase
G1 - Gap 1
S - DNA Synthesis
G2 - Gap 2
G1 Phase
• Active Growth and Metabolism
• This is where you have the most cellular activity
• The cell grows larger
• Unduplicated DNA (chromatin); cellular content, excluding the chromosomes, are
duplicated
• Final destination for adult cells:neurons and muscles (don't divide, so they don't go
thru S phase, just stay in G1, so called G0)
A particular cell has half as much DNA as some other cells in a mitotically active
tissue. The cell in question is most likely in
G1
S Phase
• Synthesis of DNA & Duplication of Chromosomes
• Twisted helix
• DNA building blocks aren't detached
• 46 chromosomes, 92 chromatids
After S phase, almost all chromosomes look like an?
X shape
G2 Phase
• synthesis of molecules in preparation for cellular division (mitosis)
• final preparations for mitosis
• Rapid production of tubulin for microtubules in formation of the spindle fibers
• cell "double checks" for any duplicated chromosomes for errors, making any needed
repairs
G0 Phase
when cells stay in G1, never entering S or G2 phase
Ex: muscle, nerve, and liver cells (unless damaged due to excess alcohol consumption,
causing the cells to go from G0→G1 resulting in liver damage & cancer)
Eukaryotic Proteins
histones and non-histones
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