unit 5: cell cycle (terms)

DNA

the molecule that carries genetic instructions for all living organisms

chromatin

the loose, thread-like form of DNA found in the nucleus when the cell is not dividing (spaghetti)

chromosome

a tightly coiled structure of DNA and proteins, which is visible during cell division (sausage)

centromere

the region of a chromosome that holds two chromatids together

chromatid

one of the two identical halves of a replicated chromosome

karyotype

a picture showing the complete set of chromosomes in a cell, arranged by size and shape

replication

the process of copying DNA before cell division

synthesis

the phase in the cell cycle when DNA is replicated

sexual reproduction

reproduction involving two parents, combining genetic material to produce unique offspring

aesexual reproduction

reproduction involving only one parent, producing genetically identical offspring

binary fission

a single cell splits into two identical cells (common in bacteria)

fragmentation

an organism breaks into parts, and each part grows into a new individual

budding

a new organism grows from the body of the parent and detaches

spawning

releasing eggs and sperm into the environment for external fertilization

copulation

sexual reproduction involving the physical union of two organisms

mitosis

a type of cell division that produces two identical daughter cells

parent cell

the original cell in mitosis that divides

daughter cell

the two new cells produced in mitosis after cell division

cell cycle

the life cycle of a cell (including growth, DNA replication, and division)

interphase

the longest phase of the cell cycle, where the cell grows and prepares for division

M-phase

the part of the cell cycle when mitosis and cytokinesis occur

prophase

the first stage, where chromosomes condense and spindle fibers form

metaphase

chromosomes line up along the metaphase plate

prometaphase

the nuclear envelope breaks down, and spindle fibers attach to chromosomes

anaphase

sister chromatids are pulled apart to opposite sides of the cell

telophase

chromosomes uncoil, and two new nuclei form

cytokinesis

the cytoplasm divides, completing the cell division

gap 1

cell grows and performs normal functions (cell growth)

gap 2

the cell prepares for division after DNA replication (more cell growth and preparation)

g0 phase

a resting phase where the cell stops dividing

centrioles

structures that help form spindle fibers during cell division

spindle fibers

protein threads that move chromosomes during division

metaphase plate

the imaginary line at the center of the cell where chromosomes align

equator

the middle of the cell during division

cleavage furrow

the indentation that forms during cytokinesis in animal cells

cell plate

the structure that forms during cytokinesis in plant cells

sex chromosomes

chromosomes that determine an organism's sex (X and Y)

autosomes

all non-sex chromosomes

somatic cells

body cells that are not involved in reproduction

sex cells

reproductive cells (sperm and egg)

homologous

a pair of chromosomes with the same genes, one from each parent

diploid

cells with two sets of chromosomes (somatic cells)

haploid

cells with one set of chromosomes (sex cells)

meiosis

a type of cell division that produces four haploid sex cells

gametes

reproductive cells ( sperm and eggs)

genetic recombination

the exchange of DNA during meiosis that increases diversity

variation

differences in traits among individuals in a population

crossing over

the exchange of genetic material between homologous chromosomes

synapsis

pairing of homologous chromosomes during meiosis

tetrad

a group of four chromatids formed during synapsis

independent assortment

random separation of chromosomes into gametes

gametogenesis

the process of making gametes (sperm or eggs)

oogenesis

the formation of eggs

spermatogenesis

the formation of sperm

spermatid

an immature sperm cell

fertilization

the fusion of sperm and egg to form a zygote

zygote

a fertilized egg cell that will develop into an organism