Ch. 8 The Cellular Basis of Reproduction and Inheritance Flashcards
Life Cycle
The entire sequence of stages in the life of an organism, from the adults of one generation to the adults of the next
What are the 2 parts of the life cycle?
1) Development - fertilized egg to adult
2) Reproduction - formation of new individual from pre-existing
Sexual reproduction
2 parents each give a gamete (w/ DNA) so that a zygote is formed from fertilization.
- complex organisms
- great variation
Genome
A complete (haploid) set of an organism’s genes; genetic material
Asexual reproduction
The creation of offspring by a single parent, w/o the participation of sperm and egg, who gives up all/part of self.
- found in simple organisms
- identical offspring
Chromosomes
“Colored bodies”
A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis/meiosis
- main gene carrier of prokaryotic cells
- consist of chromatin
- # varies from species to species (46 for humans, 23 in gamete)
Where do cells come from?
Other cells
Cell division
The reproduction of a cell and perpetuates life.
Binary fission
“dividing in half”
A means of asexual reproduction in which a parent organism (single cell) divides into 2 individual of equal size
- describes cell division in prokaryotic cells
Reproduction
One of the 9 life processes required to be considered living.
- organisms are able to make more of own kind
What is the advantage and disadvantage of asexual reproduction?
Advantage: Repopulate fast
Disadvantage: Lack of variation (Evolutionary)
What does cell division accomplish?
1) Growth
- increase in size, more cells
- allows fertilized egg to become embryo to become adult
2) Maintenance
- replacing of worn out/dead cell
3) Continuity
- genetic material is passed b/w generations
What does “like begets like” mean?
Similar type of organisms produce similar type of organisms by genetic info
Chromatin
Combination of DNA and proteins that constitute eukaryotic chromosomes
- refers to the diffused, extended form taken by chromosomes
- protein structure only seen in cell division
- chromatid is half of chromosomes and contains one long DNA
Duplication
Occurs right before cell division and is the copying of genetic material.
What is the centromere?
A button that holds chromatid together and connects the spindle fibers during mitosis and meiosis
- divides at onset of anaphase during mitosis and anaphase II of meiosis
Sister chromatid
One of the two identical parts of a duplicated in a eukaryotic cell
What happens before the cell divides?
1) Duplicate all of chromosomes
2) Cell divides and sister chromatids separate
Cell Cycle
An orderly sequence of events (including interphase and mitotic phase) from the time a cell is produces to the time it divides
Interphase
The period in the eukaryotic cell cycle between cell division
- most of the cell cycle is this phase (90%)
- metabolic activity is very high
- chromosomes duplicate, cell parts made, cell grows
- DNA synthesis
What are the 3 sub phases of interphase?
1) G1
2) S
3) G2
What occurs during G1?
Gap of time from after cell division to S phase
- half the size of normal size
- cell increases protein supply, # of organelles, grows in size
What occurs during S phase?
Synthesis (duplicating)
- DNA replication
- chromatid to chromosome
What occurs during G2 phase?
Gap of time after synthesis and to cell division
- proteins synthesized
What are the two processes of cell division?
1) Mitosis
2) Cytokinesis
Mitosis
Division of nucleus and its material
- unique to eukaryotes
- 4 phases
Cytokinesis
Division of cytoplasm and organelles
Mitotic phase (M)
Part of cell cycle with division
- Mitosis and cytokinesis
What are the 4 phases of mitosis?
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
What is the Cell Cycle Control System?
A set of proteins in the cells that trigger and coordinate cell cycle.
- 3 check points in G1, G2, M phase with proteins
When does cleavage furrow form?
Late anaphase
During telophase…
Identical daughter cells formed from parent cel but only half the size
What is the difference between animals and plants during mitosis?
Plants have no cleavage furrow or centrioles. Due to the presence of a cell wall, cell plate is formed.
What are the three factors that affect cell division?
1) Anchorage Dependence
2) Density Dependent Inhibition
3) Growth factor
Anchorage dependence
Most cells don’t divide if not connected to solid surface
Density dependent inhibition
Too dense population, slows down cell division
Grown factor
Protein secreted cause cells to divide and lack of protein can inhibit cell division
Somatic cells
Body cells
- for humans, contain 46 homologous chromosomes (23 pairs)
- full set of chromosomes that are diploid (2N)
Homologous chromosomes
The two chromosomes that make up a matched pair in a diploid cell
- same length, centromere position, and staining pattern and possess genes for the same characteristic at corresponding loci
- one inherited from father, one mother
What are the two types of homologous chromosomes?
1) Autosomes (pair 1 - 22)
2) Sex chromosomes (pair 23)
What type of cells does meiosis produce?
Gametes
Gametes
Sex cells
- haploid cells (N) with 1/2 set of chromosomes (23)
- sperm and egg
What are the divisions and products of meiosis and mitosis?
Meiosis occurs in genomes with 2 divisions for 4 haploid cells.
Mitosis has 1 division for 2 diploid cells.
What occurs during interphase of meiosis?
Spermatocyte or oocyte
What occurs during meiosis I prophase I?
Crossing over and tetrad formation
Prophase
The first stage of mitosis, during which duplicated chromosomes condense to form structures visible with light microscope and the mitotic spindle forms and begins moving the chromosomes toward the center of the cell
Metaphase
The second stage of mitosis, during which all the cell’s duplicated chromosomes are lined up at an imaginary plane equidistant b/w the poles of the mitotic spindle
Anaphase
The third stage of mitosis, beginning when sister chromatids separate from each other and ending when a complete set of daughter chromosomes have arrived at each of the two poles of the cell
- occurs with cytokinesis as cleavage furrow starts
Telophase
The fourth and final stage of mitosis, during which the daughter nuclei form at the two poles of a cell
Mitotic spindle
A spindle shaped structure formed of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis/meiosis
Centrosome
Material in the cytoplasm of a eukaryotic cell that gives rise to microtubules; important in mitosis/meiosis
- microtubule-organizing center
How does cytokinesis differ between animal and plant cells?
Animal cells... - occurs thru cleavage - cleavage furrow Plant Cell - Membrane-enclosed vesicles collect at middle of parent cell - Cell plate
Cleavage furrow
The first sign of cytokinesis during cell division in an animal cell
- shallow grove in the cell surface near old metaphase plate
Cell plate
A double membrane across the midline of a dividing plant cell, b/w which the new cell wall forms during cytokinesis
Cancer
A disease that involves abnormal cell division
- unrestrained proliferation ability
- 2nd leading killer
Tumor
An abnormal mass of cells that forms w/in otherwise normal tissue
Benign tumor
An abnormal mass of cells that remains at its original site in the body
- “friendly” doesn’t endanger life
- little deviation from normal
Malignment tumor
An abnormal tissue mass that can spread into neighboring tissue and other parts of the body; a cancerous tumor
- penetrate deeply, spread rapidly
- not removed = death
- must be detected before metastasis
Metastasis
The spread of cancer cells beyond their original site
Carcinomas
Cancer that originates in the coverings of the body
Sarcomas
Cancer of the supportive tissue
Leukemia
Type of cancer of the blood-forming tissue characterized by an excessive production of white blood cells and an abnormally high # of them in the blood
- cancer of bone marrow produces leukocytes
Lymphoma
Cancer of the tissues that from white blood cells
- tries to destroy self
Locus
The particular site where a gene is found on a chromosome
Autosomes
A chromosome not directly involved in deterring the sex of an organism
Sex chromosomes
A chromosome that determines whether an individual is male or female
Diploid cells
In an organism that reproduces sexually, a cell containing two homologous sets of chromosomes, one inherited from each parent (2N)
Haploid cells
In the life cycle of an organism that reproduces sexually, a cell containing a single set of chromosome (N)
Fertilization
The union of the nucleus of a sperm cell w/ the nucleus of an egg cell, producing a zygote
Zygote
The fertilized egg, which is diploid, that results from the union of a sperm cell nucleus and an egg cell nucleus
Meiosis
In a sexually reproducing organism, the division of a single diploid nucleus into 4 haploid daughter nuclei
- produces the haploid gametes
Cancer Cells
Lack a functioning cell cycle control system
- divide continuously (skip G1 & G2)
- steals nutrients from healthy cells (aggressive)
How do normal cells become cancerous?
1) No anchorage dependence
2) No density independent inhibition
3) No checkpoints in cell cycle
4) No fixed # of division control
What are characteristics of cancer cells?
1) Abnormal # of chromosomes
2) Cell multiplication rate changes
3) Irregular in size/shape
4) Dedifferentiation (Change shape, lose of specialized function)
5) Consume more than their share of nutrients
6) Rapid metabolism (reproduce at alarming rate)
7) Can grow anywhere in body
8) Develop resistance to harsh treatments
Oncology
Study of cancer
Oncagenes
Genes that are dominant in all people until activated
Carcinogens
Cancer causing agents that turn on oncogenes
Ames Test
Tests done to see if a substance is a carcinogen
What are biological causes of cancer?
1) Heredity
2) Age
3) Gender
4) Hormones
5) Viruses
* Stress
What are environmental causes of cancer?
1) Occupational exposure
2) Chronic irritation
3) Customs + Habits
4) Chemicals
5) Radiation
* Stress
What are treatments for cancer?
Surgery, radiation, chemotherapy
What are 8 warning signals of cancer?
1) Unusual bleeding/discharge
2) Lump/thickening
3) Sore that doesn’t heal
4) Change in bowel or bladder habits
5) Hoarseness or cough that persists
6) Indigestion
7) Change in a wart/mole
8) Unexplained weight loss
Crossing Over
The exchange of segments b/w chromatids of homologous chromosomes during synapsis in prophase I of meiosis
- adds variation
Chiasma
The microscopically visible site where crossing over has occurred b/w chromatids of homologous chromosomes during prophase I of meiosis
Genetic recombination
The production, by crossing over and/or independent assortment of chromosomes during meiosis, of offspring with allele combinations direct from those in parents
What are 3 sources of genetic variability?
1) Crossing over during prophase I
2) Independent orientation of chromosomes at metaphase I
3) Random fertilization
Karyotype
A display of micrographs of the metaphase chromosomes of a cell, arranged by size and centromere position
Trisomy 21
3 #21 chromosomes
Downsyndrome
A human genetic disorder resulting from the presence of an extra chromosome 21
Nondisjunction
An accident of meiosis or mitosis in which a pair of homologous chromosomes or a pair of sister chromatids fail to separate at anaphase
- mess up at meiosis I = all gametes abnormal
- mess up at meiosis II = half normal, half abnormal
What are the 3 types of breakage of a chromosome that can result in rearrangements that affect the genes of a chromosome?
1) Deletion
2) Duplication
3) Inversion
Deletion
Loss of one+ nucleotides from a gene by mutation; the loss of a fragment of a chromosome (serious)
Duplication
The repetition part of a chromosome resulting from fusion w/ a fragment from a homologous chromosome
- can result from an error in meiosis or mutagenesis
Inversion
A change in a chromosome resulting from reattachment in a reverse direction of a chromosome fragment to the original chromosome
- mutagen & errors during meiosis
- less harmful as all genes are present in normal #
Chromosomal translocation
A change in a chromosome resulting from a chromosomal fragment attaching to a non homologous chromosome
