Unit 4 Flashcards
What are three reasons for cell division in organisms?
renew, replace, and growth
What is a cell’s genome?
All DNA in a cell(one or multiple molecules)
DNA molecules within a cell are packaged into?
DNA molecules within a cell are packaged into?
chromosomes
What is the “building material” of chromosomes?
Protein and DNA
Differentiate between somatic cells and gametes in terms of genetic contents and function?
Somatic cells have two sets of chromosomes(non reproductive cells and diploid) while gametes have one set of chromosomes and are reproductive cells and are haploid.
What is the cell cycle?
Events a cell goes through to divide and cell duplicates
What are the 4 stages of the cell cycle?
G1, S, G2, and M
Name the 3 phases of interphase.
G1(first gap), S(synthesis), G2(second gap)
What happens during G1?
Growth
What happens during the S phase? Why is this crucial to cell division?
the cell grows and DNA is replicated (so the cell can become daughter cells-2 separate cells)
In a duplicated chromosome what are the two identical strands called? What is the “waist” called?
Sister chromosomes. Waist=centromeres
What happens during the G2 phase?
Growth and duplicated organelles
What 2 stages make up the M phase?
Mitosis and cytokinesis
What are the 5 stages of mitosis?
Prophase, Prometaphase, metaphase, anaphase, telophases
• What occurs in prophase? Prometaphase?
Chromosomes condense/ spindle fibers form. In prometaphase kinetochores appear and nuclear envelope disappears
• What is a kinetochore? Distinguish between kinetochore microtubules and nonkinetochore microtubules.
Kinetochore= attache and help chromosomes pull apart
Nonkinetochore-push against each other
What three structures make up the spindle apparatus?
Spindle microtubules, centrosomes, and the asters
What is a centrosome? What organelles are located in the centrosome in animal cells? Where are they located during mitosis?
centrosome=a type of microtubule organizing center
2 centrioles
In opposite sides of a cell
• What occurs in metaphase? Anaphase?
Metaphase= chromosomes align in the center of the cell and two centrosome are on opposite sides of the cell
Anaphase: Sister chromatids separate (pulled towards opposite ends of the cell)
• Explain the processes (there are two ways) of kinetochore microtubules moving chromosomes toward the poles of the cell.
Motor proteins at spindle poles and microtubule depolymerize
Centrosomes pulls microtubules
What occurs during telophase?
A cell is starts divided into two daughter cells, DNA uncoils, Nuclear envelope forms
Differentiate between cytokinesis in plant and animal cells. What is the name of the groove formed in animal cells? The dividing structure in plant cells?
In plants cytokinesis is done through a cell wall and the dividing structure is called a cell plate.
In animals cytokinesis happens through cleavage and the grove is called cleavage furrow
What type of division occurs in prokaryotes?
Binary fission
Explain binary fission.
Binary fission helps prokaryotes reproduce asexually and is a type of cell division. A cell duplicates and so does the genetic material forming an identical prokaryotic/organism. No phases just copy DNA and paste it into two lumps/cells
How many chromosomes do most prokaryotes have?
One
What support do scientists have of the idea that mitosis evolved from simpler prokaryotic mechanisms of cell division?
Prokaryotes came before eukaryotes and therefore miosis probably came from binary fission
Distinguish between the G1 checkpoint, the G2 checkpoint and the M checkpoint. Why is the G1 checkpoint dubbed the “restriction point”in mammalian cells?
G1= went through G1, G2=chromosomes in the middle, M= microtubules aligned and kinetochores are attached
G1 can make a cell switch to a nondividing state if the cell did not complete the G1 process (growth)
What is G0? What kinds of cells in the human body remain in G0?
G0 is the nondividing state of cell division and it has cells that never divide
What are the two types of regulatory proteins that are involved in cell cycle control?
Cyclins/ protein kinases(activate or inactivate other proteins phosphorylating them
What is a common protein released by certain cells that stimulates other cells to divide?
-Growth factors
What happens in “density dependent inhibition”?
Crowded cells stop dividing
What is Anchorage dependence?
-When cells must be attached to a substratum in order to divide (a surface)
What kinds of cells would not respond to density dependent inhibition?
Cancer cells
Differentiate between benign and malignant tumors.
Bening= stay in the same place it was produced
Malignant tumors= Spread to different organs/tissues and damage the functions of organs
What does it mean when cancer metastasizes?
Cancer metastasis means that cancer cells spread to different locations away from the the original site of the cancer cells
What is heredity?
-When traits transmit from one generation to the next
What is the scientific study of heredity and variation?
Genetics
What are the units of heredity called?
Genes
How many sets of chromosomes are inherited from each parent?
one
What term describes a gene’s specific location along the length of a chromosome?
-locus
What are reproductive cells called?
Gametes
Differentiate between sexual and asexual reproduction.
- Sexual= Only one parent, offspring is identical to parent= clone
- Asexual= Two parents, unique combination of genes that result from both parents (sex cells are used)
What is a karyotype?
An ordered display of of the pairs of chromosome from a cell
Differentiate between autosomes and sex chromosomes.
- Autosome- any chromosome that is not a sex chromosome
- Sex chromosome- determine the sex of an organism/ individual (xx=female xy=male)
What sex chromosomes are in males? Females? Sperm Cells? Egg Cells?
- xx=female xy=male
- Sperm cells= males= x or y
- Egg cells=female= x
What does it mean when cells are diploid or haploid? Give an example of diploid and haploid cells in the human body.
Haploid- A gamete (single set chromosomes) (n)
Diploid- Two sets of chromosomes (2n)
What is a karyotype? How is it useful?
- An ordered display of of the pairs of chromosome from a cell
- Karyotypes help figure out what’s going wrong in chromosome
What process must occur to form sex cells? Why is this process necessary and mitosis is not?
- Meiosis
- Meiosis contains one chromosome from each parent to form a sex cell
What is a zygote?
-A fertilized egg
What does it mean to have “alternation of generations? In a life cycle?
Two multicellular stages
Give an example of a type of organism with this kind of life cycle.
-plants and algae
In the life cycle of fungi and some prokaryotes, is the adult haploid or diploid?
Haploid (sex cells
In all life cycles, what kind of cells (haploid or diploid) can undergo meiosis? What cell type(s) (haploid or diploid) can undergo mitosis?
meiosis= diploid cells mitosis= either cells
What occurs in interphase before meiosis? Does this differ from interphase in mitosis?
Chromosomes are paired in homologous pairs
In interphase in mitosis the chromosomes don’t have homologous pairs (there is only one chromosome)
Compare daughter cells at the end of Meiosis I and Meiosis II.
- Meiosis I= 2 daughter cells (sister chromatids are still connected)
- Meiosis II= 4 daughter cells (sister chromatids are separated
What four stages make up Meiosis I?
- Interphase I
- Metaphase I
- Anaphase I
- Telophase I
What is synapsis?
A zipper-like structure called the synaptonemal complex
When two chromosomes pair together What is a tetrad?
2 homologous pairs together (4 chromatids/ strands of DNA )
What is crossing over?
When non-sister chromatids exchange DNA segments
Which chromatids exchange genetic material during prophase I?
Homologous chromosomes
What is an X-shaped region where crossing over has occurred?
Chiasmata
What is a synaptonemal complex and when does it occur?
- Synapsis
- During prophase I
What is the name of the protein that holds sister chromatids together during Meiosis I?
Cohesin
How do the chromosomes line up during metaphase I? How is this different from how they line up in metaphase II?
- Metaphase I- chromosomes line up in homologous pairs (but they separate)
- Metaphase II- chromosomes line up a single file (sister chromatids separate)
What occurs during anaphase I? How does this stage differ from anaphase II?
- Anaphase I- homologous pairs are separated
- Anaphase II- Sister chromatids are separated
What occurs during telophase/cytokinesis I?
2 daughter cells are formed that separate homologous pairs (2 haploid cells)
Does DNA replication occur between Meiosis I and II? Why or why not?
No because the DNA was already replicated in Meiosis I and the 2 daughter cells as a result of this process need to further divide to separate sister chromatids.
What process is Meiosis II very similar to?
Mitosis
What four stages make up Meiosis II?
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II and cytokinesis
Compare Mitosis and Meiosis in respect to the number of divisions and their role(s) in the body.
Mitosis= 1 division Meiosis= 2 divisions
-Mitosis is use for cell growth, repair, and asexual reproduction
-meiosis is used for sexual reproduction
Compare Mitosis and Meiosis in respect to the number of daughter cells and chromosome numbers in daughter cells and parent cells.
- Mitosis creates two daughter cells
- meiosis produces four daughter cells (both start with diploid cells)
- Mitosis has the same amount of chromosomes in parent and daughter cells
- Meiosis has half the amount of chromosomes from the parent cell in the daughter cells
Compare genetic variability in daughter cells formed from mitosis and those formed from meiosis.
mitosis= genetically identical cells Meiosis= genetically different cells (because it takes the DNA of two parent cell)
What three mechanisms contribute to genetic variation within a species?
- Crossing over
- Random fertilization
- independent assortment of chromosomes (whether they face forward or backwards)
What is meant by “independent assortment”?
whether they face forward or backward when they are separated (how they line up)
What does the term “recombinant chromosome” mean?
the combination of the DNA inherited from each parent (different from the parents)
Approximately how many different genetic combinations are possible in gametes produced from one human being?
8.4 million
Approximately how many different genetic combinations are possible in a zygote formed from two individuals?
70 trillion
