vocab
define ADDITION..
an extra base is added that shouldnt be there. eg cTGGag cTGGTGGag.
what is ADENINE paired with?
adenine and thymine, A + T
define ANAPHASE
the stage in mitosis after metaphase, cells and chromosomes begin to split.
define AESEXUAL REPRODUCTION
does not need male + female genetils to make life, like a clone.
define BINARY FISSION
the parent cell replicates its gentic material and divides into 2 equal parts. (type of aesexual reproduction)
define BLASTULA
a stage of embryotic development, occurs in the 2nd week.
define BUDDING
A type of aesexual reproduction, a new organism develops from a bud caused by repeated mitosis/cell division to develop and identical organism.
what is a CANCER CELL
a cell that grows out of control, it ignores the signals to stop dividing or to die/shed.
define CELL CYCLE
the life cycle of the cell, divided into 3 stages.. interphase, mitosis, cytokenisis.
what is the CELL MEMBRANE
a thin protective covering on the cell.
define CELL WALL
only appears in plant cells, protects the cell and gives it the box like shape.
define CENTROMERE
links a pair of sister chromatids together during cell division, helps the cell divide up its DNA.
define CHECKPOINT
a stage in the cell cycle when the cell "decides" whether or not to move forward with division (unlike cancer cells) 3 checkpoints occur in G1, G2, and MITOSIS.
define CHROMATIN
made of strands of DNA (found in the nucleus) + protiens. each strand of chromatin has 1 molecule of DNA.
define CHROMOSOME
tightly packed DNA + protien seen as "x" during cell division. eg XX=female, XY=male.
define CHROMOSOME MUTATION
changes in the number or structure of chromosomes. eg. POSITIVE, NEUTRAL, NEGATIVE.
define CROSSING OVER
chromotids of chromosome pairs can cross over each other and exchange DNA, encreases genetic variation.
define CYTOKENISIS
part of the cell division proccess and mitosis (5%) the seperation of 2 nuclei into 2 daughter cells.
what is paired with CYTOSINE?
cytosine and guanine, C+G
define DELETION.
a form of mutation when something is missing.
define DIPLOID NUMBER
this has 2 sets of chromosomes, one set has 23 so 23 + 23= 46
define DNA
DNA looks like a twisted ladder called a DOUBLE HELIX, the sides are made of sugar + phospahte backbone, steps are made of nitrogenous bases.
when does DOWN SYNDROME occur?
occurs when there is an EXTRA 21st chromosome.
define ENDOPLASMIC RETICULUM.
a network of membrane - covered channels, the cells highway. Rough ER + Smooth ER
EXTERNAL FERTILIZATION
happens outside of the organisms body, like salmon.
define FRAGMENTATION
fragments break off parents body from injury and that fragment produced a clone of parent. (starfish)
define GAMETE
organisms that reproduce sexually create cells w half the # of chromosomes, 2 gametes form a ZYGOTE.
define GENE
the basic materials. a small section of DNA codes for a simple protien.
GENE MUTATION
a change in the DNA sequence of a cell, can lead to gentic disorders or illness.
GOLGI BODY
sorts + repackaged protiens for delivery. produced membrane wrapped vesicles.
what is GUANINE paired with?
paired with cytosine. C + G
define HAPLOID NUMBER
the number of chromosomes in a single set (23)
define HOMOLOGOUS CHROMOSOMES
2 chromosomes w similair size, genes etcc pair up + CROSS OVER
define INTERPHASE
the majority of life cycle, made up of 3 parts G1, S, G2. cell grows, makes protiens and nucleus is visible.
define KARYOTYPE
your complete set of chromosomes, analyzes shape, size and # of chromosomes.
define MEIOSIS
a proccess that produced HAPLOID GAMETES (sex cells)
define METAPHASE
a stage of mitosis, chromosomes line up in the centre of the cell.
define MITOSIS
20% of cell cycle. contents of cells nucleus divide five steps, prophase one prophase, two metaphase anaphase telophase.
what is MORULA
stage of embryotic development. occurs at the end of the first week.
what occurs in PROPHASE
The nucleus fades away, and the chromosomes become visible
define RNA
Ribo nucleic acid half of the DNA (missing its pairs), only one side of the double helix.
what are sister chromatids?
The identical copies formed by the DNA replication of a chromosome
what happens in telophase?
The nucleus reforms around the chromosomes
what is thymine paired with?
thymine is paired w adenine
define vegetative reproduction
stems and roots divide repeatedly to form copies of the parent cell
define zygote
A fertilized, single celled organism resulting from a fertilized egg