Cell division and cellular organisation

cell theory

cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

mitosis

part of eukaryotic cell division during which the cell nucleus divides/ the term for the division of 1 cell into 2 genetically identical daughter cells

somatic cells

Any cells in the body other than reproductive cells

genetically identical

2 organisms that contain the same genetic information

asexual reproduction

A reproductive process that involves only one parent and produces offspring that are identical to the parent.

diploid

(genetics) an organism or cell having two sets of chromosomes or twice the haploid number

haploid

An organism or cell having only one complete set of chromosomes.

gametes

reproductive cells

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

the cell cycle

series of events in which a cell grows, prepares for division, and divides to form two daughter cells

homologous chromosomes

Chromosomes that have the same sequence of genes and the same structure

chromatids

Bodies of tightly coiled chromatin; visible during cell division. Two chromatids bound at a centromere make a chromosome.

centromere

the region of the chromosome that holds the two sister chromatids together during mitosis

chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

cytokinesis

Division of the cytoplasm during cell division

G1

growth phase 1: production of enzymes and proteins and the replication of organelles. Cell size increases in size

S

synthesis phase: DNA replication in nucleus

G2

growth phase 2: cell continues to increase in size, energy stores are increased, DNA is checked for errors

G0

A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.

cell-cycle checkpoints

Points of transition between different phases of the cell cycle, which are regulated by cyclins and cyclin-dependent kinases (CDKs).

G1/S checkpoint

cell determines if DNA is in good condition for synthesis controlled by protein

G2 checkpoint

The cell checks to make sure the DNA is copied correctly

spindle assembly checkpoint

checks for chromosome attachment to spindle

cyclin-dependent kinases

enzyme to which cyclin binds during interphase and mitosis, triggering and controlling activities during the cell cycle

cancer

any malignant growth or tumor caused by abnormal and uncontrolled cell division

mitotic spindle

An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis.

prophase

first and longest phase of mitosis in which the genetic material inside the nucleus condenses and the chromosomes become visible

chromatid

one of two identical "sister" parts of a duplicated chromosome

chromosome

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

centriole

one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope - forms the mitotic spindle

nuclear envelope

Double membrane perforated with pores that control the flow of materials in and out of the nucleus.

spindle fibres

network of filaments that collectively form a mitotic spindle in mitosis. They are involved in moving the chromosomes during nuclear division.

metaphase

second phase of mitosis, during which the chromosomes line up across the centre of the cell

cell equator

during mitosis and meiosis, this is where chromosomes pair up and attach to the spindle

anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

telophase

the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

cleavage furrow

The area of the cell membrane that pinches in and eventually separates the dividing cell

end plate

formed by plant cells around which new plasma membranes and cellulose cell walls are formed to separate the parent cell into 2 daughter cells

nuclear division

the division of a cell's nucleus, as in mitosis and meiosis

lactopropionic orcein

a stain used to identify chromosomes

gamete

specialized cell involved in sexual reproduction

zygote

fertilized egg

reduction division

a nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division

alleles

Different forms of a gene

bivalents

A structure in which 2 pairs of homologous sister chromatids have synapsed (crossed over) with one another

crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis. (points of cross over = chiasmata)

independent assortment

the random distribution of the pairs of genes on different chromosomes to the gametes

genetic variation

Differences among individuals in the composition of their genes or other DNA segments

chiasmata

site of crossing over

recombinant chromosomes

A chromosome created when crossing over combines the DNA from two parents into a single chromosome.

tetrad

plants - structure containing 4 chromatids that forms during meiosis

differentiation

process in which cells become specialised in structure and function

division of labour

the specialisation of cells so that they can each carry out their individual functions

specialised cells

cells that have a special job to do in the body and have a structure that makes them better able to do their job

erythrocytes

red blood cells

neutrophils

A type of white blood cell that engulfs invading microbes and contributes to the nonspecific defenses of the body against disease.

lysosomes

An organelle containing digestive enzymes

multilobed nucleus

a nucleus with multiple sections which gives neutrophils flexibility

chemotaxis

movement by a cell or organism in reaction to a chemical stimulus

phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

spermatozoa

sperm cells

undulipodia

cilia and flagella - allow cells to move

acrosome

A region at the head of a sperm cell that contains digestive enzyems which, when released during the acrosome reaction, can facilitate penetration of the corona radiata of the egg, and subsequently, fertilization

ovum

A mature egg cell

epithelium

the specialized epithelial tissue that forms the epidermis of the skin and the surface layer of mucous membranes

squamous epithelial cells

flattened epithelial cells arranged in a layer

ciliated epithelial cells

Cells in the tubes leading to the lungs that have microscopic hairs, cilia, growing from them - move mucus out of the respiratory tract to be swallowed

phloem

the vascular tissue in plants that conducts sugars and other metabolic products downward from the leaves.

meristem

Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth.

cambium

a layer of tissue that produces new vascular tissue and grows between xylem and phloem - has stem cells

xylem

vascular tissue that carries water upward from the roots to every part of a plant

lignin

substance in vascular plants that makes cell walls rigid

bordered pits

Thin areas in the lignified walls of xylem tissue cells that allow communication between adjacent cells.

sieve tube

found in phloem; stacked end to end; have holes so materials can get in and out of the phloem

companion cell

A type of plant cell that is connected to a sieve-tube element by many plasmodesmata and whose nucleus and ribosomes may serve one or more adjacent sieve-tube elements.

sieve plate

An end wall in a sieve-tube element, which facilitates the flow of phloem sap in angiosperm sieve tubes.

root hair cell

Cell found on the surface of plant roots that has a large surface area to absorb water and dissolved mineral salts quickly from the soil.

palisade mesophyll cell

Tall, tightly packed cells in a leaf. Contain lots of chloroplasts and are the major site of photosynthesis.

guard cell

specialized cell in the epidermis of plants that controls the opening and closing of stomata

tissue

a group of specialised cells that work together to perform a specific function

organ

A collection of tissues that carry out a specialized function of the body

organ system

A group of organs that work together in performing vital body functions.

basement membrane

a matrix of extracellular proteins and glycoproteins on which a tissue may be separated from another tissue

epithelial tissue

Tissue that covers outside of the body and lines organs and cavities.

connective tissue

A body tissue that provides support for the body and connects all of its parts

muscle tissue

A body tissue that contracts or shortens, making body parts move.

nervous tissue

A body tissue that carries electrical messages back and forth between the brain and every other part of the body.

squamous epithelium

a layer of flattened platelike cells that cover internal and external body surfaces

ciliated epithelium

A layer of cells that have many hair-like extensions called cilia

cartilage

A connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together.

muscle

tissue composed of fibers that can contract, causing movement of an organ or part of the body

smooth muscle

Involuntary muscle found inside many internal organs of the body

skeletal muscle

A muscle that is attached to the bones of the skeleton and provides the force that moves the bones.

cardiac muscle

Involuntary muscle tissue found only in the heart.

hyaline cartilage

The most abundant cartilage type in the body; provides firm support with some pliability - in the young skeleton and joins fibs to the sternum

fibrous cartilage

very tough form of cartilage found in the intervertebral disks of the spine and at the junctions where tendons attach to bone

elastic cartilage

cartilage with abundant elastic fibers; more flexible than hyaline cartilage - in the external ear and parts of the trachea to keep it open

chondroblasts

within the cartilage divide and secrete new matrix