Biology Chapter 6 Keywords - Cell Division

6.1 cell cycle

highly ordered sequence of events that take place in a cell. results in the division of the nucleus and the formation of 2 genetically identical daughter cells

6.1 interphase

growth period of the cell cycle between cell divisions (mitotic phase). consists of G1, S and G2

6.1 mitotic phase

cell division during the cell cycle. consists of mitosis and cytokinesis

6.1 senescent

cells that are permanently no longer able to replicate

6.1 checkpoint

control mechanisms of the cell cycle

6.1 kinase enzymes

enzymes that catalyse an addition to the phosphate group of a protein

6.1 cyclin

checkpoint proteins that can form cyclin dependent kinase complex (CDK)

6.1 phosphorylation

addition of a phosphate group to a molecule

6.1 tumour

an abnormal mass of cells

6.1 benign

non cancerous, slow growing tumours. they do not invade other tissues, but can cause damage

6.1 malignant

unchecked, uncontrolled, quick growing, cancerous tumour

6.1 telomeres

• caps at the end of chromosomes, which get shorter at every replication

• sets the hayflick limit

6.1 hayflick limit

where cells can only go though the cell cycle a certain number of times

6.2 asexual reproduction

the production of genetically identical offspring from a single parent cell

6.2 binary fission

asexual reproduction in prokaryotes, resulting in genetically identical offspring from one cell

6.2 mitosis

the nuclear division stage in the mitotic phase of the cell cycle

6.2 chromosome

condensed DNA wrapped around histones, which are only seen the mitotic phase and under a light microscope

6.2 chromatid

a sister chromatid after separation

6.2 centromere

un-replicated section of the chromosome where the sister chromatids are joined

6.2 prophase

• first stage of mitosis when chromatin condenses to form visible chromosomes

• the nuclear envelope breaks down

• spindle fibres attach to centromeres and start to move chromosomes to the equator

6.2 metaphase

where chromosomes arrange in a single line along the equator of a cell

6.2 anaphase

spindle fibres contract and pull sister chromatids to opposite poles of cell

6.2 telophase

• nuclear envelope and nucleolus reforms

• chromosomes uncoil

• becomes long and thin and uncondensed (chromatin)

6.2 cytokinesis

cell division phase of the cell cycle that results in the production of 2 identical daughter cells

6.2 cleavage furrow

a groove that forms on the surface of an animal cell during cell division

6.3 gametes

haploid sex cells produced by meiosis in organisms that reproduce sexually

6.3 zygote

diploid cell formed when 2 gametes are joined by sexual reproduction. it is the earliest stage of embryonic development

6.3 meiosis

a form of cell division where the nucleus divides twice, resulting in the halving of the chromosome number and 4 genetically unique haploid cells

6.3 haploid

half the normal chromosome number. one unpaired copy of each type of chromosome

6.3 reduction division

meiosis/cell division resulting in the production of haploid cells from a diploid cell

6.3 homologous chromosomes

matching pair of chromosomes, one inherited from each parent

6.3 diploid

2 copies of each chromosome

6.3 locus

position of a gene/allele on a chromosome

6.3 alleles

version/form of a gene

6.3 meiosis I

first version of two cell divisions, where a diploid parent cell divides to form 2 haploid cells

6.3 meiosis II

second stage of the 2 cell divisions, where the two haploid cells produced in meiosis I divide into 4 genetically unique daughter haploid cells

6.3 bivalents

a pair of a homologous chromosomes

6.3 crossing over/chiasmata

sections of DNA where chromosomes cross over each other and break off during anaphase 1, exchanging DNA between bivalent chromosomes.

results in the formation of recombinant chromatids and genetic variation

6.3 independent assortment

the arrangement of each homologous chromosome in metaphase 1 and metaphase 2 which are independent of each other and results in genetic variation

6.3 chiasmata

sections of DNA in chromosomes which cross over each other

6.3 recombinant

chromatids with new combinations of alleles/DNA

6.3 genetic variation

a variety of different combinations of alleles in a population

6.4 multicellular

multiple cells that are specialised and work together to perform functions

6.4 specialised

having particular structure to perform a specific function

6.4 differentiated

the result of differentiation - a specialised cell

6.4 erythrocyte

red blood cell

6.4 neutrophil

type of white blood cell that is phagocytic (ingests microbes and small particles)

6.4 tissue

group of cells that work together to perform a specific function/set of functions

6.4 squamous epithelium

tissue made form thin, flat squamous epithelial cells, which covers and lines free surfaces

6.4 ciliated epithelium

made of ciliated epithelial cells and goblet cells. it has hair like projections, which beat in a rhythm to move substances. it lines the oviduct and trachea

6.4 chondrocyte cells

mature, differentiated chondroblasts maintain the matrix in cartilage

6.4 cartilage

strong, flexible connective tissue found in joints, trachea, nose and ears

6.4 epidermis tissue*

single layer of closely packed cells, which cover the surface of plants

6.4 vascular tissue

transport tissue - composed of the xylem and the phloem

6.4 xylem tissue

plant transport tissue that carries water and minerals from roots to other part of the plant

6.4 phloem tissue

plant transport tissue that carries products of photosynthesis to all cells of the plant

6.4 organ

a group of tissues working together to perform a function

6.4 organ system

a group of organs working together to perform a function

6.5 differentiation

the process where unspecialised stem cells become specialised into different types of cell

6.5 undifferentiated

an unspecialised cell originating form mitosis or meiosis

6.5 stem cells

undifferentiated cells that are able to express all their genes and divide by mitosis

6.5 potency

the ability of stem cells to differentiate into different cell types

6.5 totipotent

a stem cell that can differentiate into any type of cell and form a whole organism and placental cells

6.5 pluripotent

a stem cell that can differentiate into any type of cell, but not from a whole organism and cannot form placental cells

6.5 multipotent

a cell that can only differentiate into a limited range of specialised cell types, within a certain type of tissue

6.5 bone marrow

tissue within bones which can contain multipotent cells which can differentiate into all types of blood cells

6.5 embryonic stem cells

undifferentiated cells from embryos that are pluripotent

6.5 adult stem cells

unspecialised, multipotent cells that are found in many organs of the body

6.5 meristematic tissue

tissue found at regions of growth in plants, contains meristem cells

6.5 meristems

plant stem cells - found at any growing point (e.g. roots) and sandwiched between xylem and phloem

6.5 blastocyte

a ball of cells formed in the early embryo

made of pluripotent cells and surrounded by stem cells which will develop into placenta and umbilical cord