Final Flashcards
What are the factors that regulate cell size?
demands on DNA: more materials are needed to carry out cell processes as a cell increases in size; the cell must divide since DNA cannot keep up with the demand once the cell reaches a certain size
exchange of materials: as S:V goes down, the exchange becomes less efficient; food, water, oxygen, and necessary ions are brought in while waste leaves and is removed
What is the surface area to volume ratio?
as a cell gets larger, the S:V goes down–the volume gets bigger than the surface area
asexual reproduction
simple cell division
What are the advantages and disadvantages of asexual reproduction?
advantages: takes less time, is done individually, produces offspring that are genetically identical to the parent
disadvantages: is small/restricted in size and simple
sexual reproduction
fusion of 2 nuclei-needs 2 things to reproduce
What are the advantages of sexual reproduction?
- produces diverse offspring
- produces offspring that have a better chance of survival if the environment changes
- is large and complex
cell cycle
preparation for the division of cells
What are the phases of the cell cycle?
G1 (1st Gap Phase): cell growth where DNA is assessed
S Phase (Synthesis): DNA replication
G2 (2nd Gap Phase): assessment of DNA replication and production of organelles and molecules specific to cell division where DNA is checked to see if it copied properly
M phase: mitosis and cytokinesis where DNA is checked to see if it is separating properly
cytokinesis: division of the cytoplasm and its contents
apoptosis
cell death
What are regulators of the cell cycle?
cyclins: proteins that regulate the timing of the cell cycle in eukaryotic cells-chemical signals tell the cell when to divide and proceed to the next phase of the cell cycle
internal regulators: cyclins that respond to events inside the cell-proteins make sure that the cell does not enter mitosis until the DNA is copied correctly and prevent the cell fro, entering anaphase before all the chromosomes attach to the spindles
external regulators: cyclins that respond to events outside of the cell-directs cell to speed up or slow down the cell cycle
mitosis
division of the nucleus and DNA
What are the phases of mitosis?
prophase: breakdown of nuclear membrane-centrioles separate and spindles form
metaphase: chromosomes line up at the equator of the cell and spindles attach to centromeres of the chromosomes
anaphase: chromatids separate from each other and become chromosomes that migrate along the spindles to opposite ends of the cell
telophase: chromosomes reach opposite ends of the cell and distend into chromatin-nuclear membrane forms
cytokinesis: cytoplasm is divided and the cell pinches in half-a cell plate that will eventually develop into a cell wall forms between the two cells
cancer
an overriding of cells that stop cell division
What causes cancer?
- tumors: masses of abnormal cells
- smoking
- radiation exposure
- viral infection
- chemical exposure
- p53: gene that allows a build-up of cells that do not respond to regulation
cell specialization
cells evolve to form cells that have specific functions
cell division
the cell divides to produce two “daughter cells”–replicates the DNA so each new cell gets a complete set
diploid
a full complement of chromosomes (2N)
haploid
half of the full diploid complement (N)
meiosis
the reduction of chromosomes for sexual reproduction
What are the phases of meiosis?
interphase I: cells undergo a round of DNA replication, forming duplicate chromosomes
prophase I: each chromosome pair with its corresponding homologous chromosome cross over to form a tetrad
metaphase I: spindle fibers attach to the chromosomes
anaphase I: the fibers pull the homologous chromosome toward opposite ends of the cell
telophase I+cytokinesis I: nuclear membranes form and the cell separates into two cells
prophase II: results in two haploid daughter cells that each have half the number of chromosomes as the original cell
metaphase II: the chromosomes line up in a similar way to metaphase in mitosis
anaphase II: the sister chromatids separate and move toward opposite ends of the cell
telophase II+cytokinesis II: results in 4 haploid cells
gene
a chemical factor that determines traits-codes for protein production
gene
a chemical factor that determines traits–codes for protein production
allele
different forms of the same gene–particular expression of a gene
dihybrid
two different genes are passed from one generation to the next
complete dominance
identical phenotypes of the dominant homozygote and heterozygote
