unit 7 Flashcards
What are the two types of reproduction?
Sexual and Asexual
How are offspring produced in asexual reproduction?
Offspring are produced from a single organism
What are the effects of asexual reproduction?
It’s simple and efficient and offspring are genetically identical.
How are offspring from sexual reproduction produced?
Offspring are produced by fusion of reproductive cells from two parents
What are the effects of sexual reproduction?
It increases genetic diversity
How are prokaryotic cells divided?
Divided by binary fission to produce two identical daughter cells
How are eukaryotic cells divided?
Divided by mitosis to produce two identical daughter cells
What type of reproduction are binary fission and mitosis?
Asexual reproduction
What are somatic cells?
Eukaryotic cells that divide by mitosis
What cells make up our bodies?
Somatic cells
When do body cells divide?
When an organism is growing or it needs to replace old or damaged cells
What is interphase?
The part of the cell cycle where cells spend the most time and perform their normal function or job
Gap 1 (G1) phase
Cell growth
S phase
DNA replication
Gap 2 (G2)
Cell growth and preparation for division
M phase
Cell division
What is mitosis?
When DNA and the nucleus separate
What are the 4 stages of mitosis?
Prophase, metaphase, anaphase, telophase (PMAT)
Cytokinesis
Parent cell separate into 2 daughter cells
What is cancer?
A disease that occurs when a cell divides when it should not
How are tumors formed?
Unregulated cell division leads to a pileup of cells that form a lump (a tumor)
What are genes?
Instructions found on DNA for building all proteins that a cell requires
What is chromatin?
Unwound and uncondensed DNA
What is a chromosome?
wound and condensed DNA
When do chromosomes exist?
Only during cell division
What are sister chromatids?
Identical copies of DNA attached together to make a chromosome
When do sister chromosomes exist?
Only exist after DNA replication and after the S phase
What is a centromere?
The middle of a replicated chromosomes
What is at the end of chromosomes?
Telomeres
What is the purpose of mitosis?
2 identical daughter cells
When does DNA replication occur?
Before mitosis, during S phase.
Which phase is the longest phase of mitosis?
Prophase
What happens during prophase?
DNA condenses into chromosomes
Centrioles moves to the opposite “poles” of the cells and send out spindle fibers
Nuclear envelope breaks down and nucleolus disappears
Why does DNA condense into chromosomes?
This allows them to take up less space
What is the shortest phase of mitosis?
Metaphase
What happens during metaphase?
All the chromosomes are lined up across the equator (center) of the cell
Spindle fibers attach to the centromeres of the chromosomes
Each sister chromatid is attached to a spindle fiber originating from opposite poles
What happens during anaphase?
Sister chromatids break apart and are now called daughter chromosomes
Daughter chromosomes are pulled to opposite poles of the cell by spindle fibers
Spindle fibers that aren’t attached to chromosomes elongate the cell
What happens during telophase?
Chromosomes arrive at opposite poles of the cell and begin to decondense
Nuclear envelope begins to reform and spindle fibers break down
What is cytokinesis?
Cell splitting
What happens during cytokinesis?
The cell and its contents (organelles, cytosol) divide into two daughter cells
How do animals use cytokinesis?
Cleavage furrow forms from a contractile ring of microfilaments
How do plants use cytokinesis?
Cell plate forms as vesicles containing cell wall materials travel to the equator
What is the order of the cell cycle?
1) Interphase (G1, S phase, G2)
2) Cell division (Mitosis, Cytokinesis)
What stage of cell division is this?
Before mitosis
What stage of cell division is this?
Prophase
What stage of cell division is this?
Metaphase
What stage of cell division is this?
Anaphase
What stage of cell division is this?
Telophase
What stage of cell division is this?
Cytokinesis
What is meiosis?
Cell division that produce daughter cells called gametes
What is different about gametes?
They only contain half the normal number of chromosomes
Why do gametes only contain half the normal chromosomes?
Because gametes combine to form an embryo
What is a gamete?
A haploid because they contain half the chromosomes
What are somatic cells?
Diploid because they contain twice the number of chromosomes than haploid cells
How many chromosomes are in human somatic cells?
46 chromosomes (23 pairs)
What are pairs of chromosomes called?
Homologous pairs
What are gene variations called?
Alleles
What determines the sex of an individual?
Sex chromosomes
Males=XY
Females=XX
What are autosomes?
Nonsex chromosomes
Humans have 22 pairs
How many chromosomes are in human diploid cells?
46 chromosomes
How many chromosomes are in human haploid cells?
23 chromosomes
What can only be produced by meiosis?
Gametes
What is mitosis only for?
Body cells
What is the end product of mitosis?
2 genetically identical cells
What is the end product of meiosis?
4 haploid cells (half the chromosomes)
How many times does meiosis go through PMAT/cytokinesis?
2 times
What happens with the genetic material in meiosis?
We will see a possibility of swapping genetic material between homologous pairs
What is swapping genetic material called?
Crossover
When does crossover occur?
ONLY occurs in Prophase 1 of meiosis
How do the chromosomes line up in meiosis 1?
Randomly across the equator
Allows the chromosomes from mom and dad to be mixed up in the gametes
What is nondisjunction?
When chromosome pairs fail to seperate