DNA replication and cell division Flashcards
reproduction
to survive, a species must reproduce
two types of reproduction
asexual and sexual
how sex cells reproduce (sexual)
meiosis
how somatic cells reproduce (sexual)
mitosis
Asexual reproduction
Genetic material and organelles are replicated; the cell divides into 2; genetically identical offspring; binary fission
meiosis
genetic material comes from 2 parents
gametes
sex cells that have half of the genetic material - genetic material is ‘mixed’ and redistributed
fertilization
egg and sperm unite to form 1 complete cell
mitosis
genetic material comes from 1 parent cell (type of asexual reproduction that sexually reproducing organisms do)
What is mitosis important for?
growth, repair, regeneration, reproduce (protists – asexually)
apoptosis
cell death - scheduled – normal part of development and very important for an organism - cell division and apoptosis occur at the same rate - they are ‘balanced’ so tissues don’t become too large or shrink
examples of apoptosis
chicken feet, duck feet, tadpole tail, sunburnt skin
DNA replication
before a cell divides it first must replicate its genome
How many chromosomes do humans have?
46
how many chromosomes do bacteria have
only 1
DNA replication involves many
enzymes
DNA _____ adds new DNA _____
polymerase, nucleotides
____form covalent bonds between DNA segments
ligases
Bacteria get new genetic material from
mutation, transfer through a sex-pilus, and absorption
sex-pilus
appendage/tube connecting 2 bacterial cells temporarily
absorption
bacteria can absorb bits of genetic material from a dead cell
DNA replication (prokaryote)
Parent cell contains one chromosome; DNA replicates and attaches to cell membrane; membrane growth between the two attachment points moves the DNA molecules apart as new cell wall material is deposited
The result of binary fission
two daughter cells, each identical to the original
Chromosome parts
chromatin, nucleosome, chromatid, and centromere
Chromatin
DNA and proteins
Nucleosome
DNA wrapped around 8 histone proteins
Chromatid
condensed chromosome (2) - sister chromatids
centromere
small section of DNA that attaches sister chromatids together
Phases of mitosis
interphase prophase metaphase anaphase telophase cytokinesis
Interphase
Most of the life of a cell is spent in interphase; chromosomes are not visible (chromatin is unwound); the nucleolus and the nuclear envelope are distinct and the chromosomes are in the form of threadlike chromatin
three phases of interphase
G1 phase-gap 1
S phase-synthesis
G2 phase-gap 2
G1 phase - gap 1
cell carries out its basic functions - it grows and produces molecules to build new organelles
S phase - synthesis
Cell replicates its genetic material and repairs DNA
G2 phase - gap 2
cell prepares to divide and produces proteins for mitosis
prophase
DNA coils tighter and is visible; mitotic spindle attaches to chromosomes and makes spindle fibers; centrosome (centrioles) help organize the spindle fibers; nuclear envelope breaks down; the chromosomes appear condensed and the nuclear envelope is not apparent
metaphase
chromosomes are lined up at the equator of the cell by the spindle
telophase
mitotic spindle disassembles; chromosomes begin to unwind; nuclear envelope forms; early signs of cytokinesis starting
cytokinesis
cytoplasm splits; 2 daughter cells are formed
diploid
2 sets of chromosomes (1 from each parent)
Cancer
cell doesn’t know when to stop
a normal cell has
chemical regulation to tell it when to divide and when to stop
tumor
abnormal mass of tissue
benign tumor
slow growing and usually harmless unless they get too large and interfere with other tissue; have a tough capsule surrounding mass
malignant tumor
invades adjoining tissue; no surrounding capsule so it can metastasize - cells can break off and travel to other parts of the body
genetic cancer
mutated genes inherited from parents or errors during development
environmental cancer
exposure to chemicals, radiation, viruses
How to treat cancer
removal of tissue, drug therapy, radiation therapy
chemotherapy and radiation therapy
both target rapidly dividing cells
rapidly dividing cells include
both cancerous and healthy cells
side effects of chemotherapy and radiation therapy
fatigue, hair loss, nausea, weakened immune system
success of treatment depends on
type of cancer, stage of cancer, where it is located, and if it has metastasized or moved
