Unit 8: Chromosomes, Cells, & Cell Division

cell division

process of cells dividing and creating 2 new cells

cell theory

all living things are made of cells

how cell theory relates to cell division

all cells come from existing cells

purpose of cell division

replacement, development & growth, size

cell development & growth

cell division allows organisms to grow from a single-celled organism to a complex multicelled organism

cell replacement

RBCs only live 4 months (ex: starfish grow new arms via cell division)

cell size

limitation of cell size -cells can only be so big!

asexual reproduction

process by which a single parent reproduces by itself

difference between asexual and sexual reproduction

asexual involves 1 parent while sexual involves 2

why some cells might divide more than others

the function of different cells determines their division rate (ex: epithelial cells divide at faster rates than muscle cells) genetic mutations may also cause unregulated cell division

DNA

long/thin molecule (can't see it)

how DNA compacts itself

to fit into the nucleus, the DNA has to get really compact

histones

proteins that DNA wraps itself around to get more compact

chromatin

clusters of DNA and histones (protein)

chromosomes

linear structures of protein and DNA organized into genes

non-replicated chromosome

has one DNA molecule and is made up of one chromatid

replicated chromosome

two identical DNA molecules (sister chromatids) attached at a centromere

before DNA wraps itself into a chromosome

DNA replication occurs and the DNA condenses to form chromatin

chromatid

one of two identical halves of a chromosome

sister chromatids

joined copies of two chromatids that make up a replicated chromosomes (identical and connected)

centromere

area where sister chromatids are connected

how many chromosomes does a human have?

46 (23 from mom, 23 from dad)

cell cycle

complete life cycle of a cell

two main stages of cell cycle

interphase, mitotic phase

interphase

cell growth, DNA replication, prepares for division, and normal cell activities

G0 phase

period when cell is not preparing to divide

stages of mitosis

prophase, metaphase, anaphase, telophase

prophase

Chromosomes become visible, the nuclear envelope dissolves, organelles break down and disappear, and the spindle forms

what happens to spindle fibers during metaphase?

spindle fibers fully form and attach to the centromeres of chromosome pairs.

where do chromosomes line up during metaphase?

in the middle of the cell.

anaphase

sister chromatids are pulled apart by spindle fibers towards polar ends of the cell

telophase

new nuclei form around each set of chromosomes, and two new cells start to take shape, chromosomes begin to make proteins

cancer

disease where the body's cells do not stop mitosis

how does cancer develop

cell gets mutation and a tumor is created

meiosis

special type of cell division that produces gametes with half the number of chromosomes

somatic cell

body cells, have full set of chromosomes

gamete

reproductive cells (sperm or eggs) have half the number of chromosomes

homologous chromosomes

pairs of chromosomes that are the same size, shape, and gene type

diploid

paired chromosomes, full set

example of diploid cell

body cells

haploid

cells that have half the number of chromosomes, unpaird

example of haploid cell

gametes

mitosis

process of cell division, making 2 identical daughter cells

zygote

fertilized egg (diploid)

step 1 of meisosis

chromsomes duplicate

step 2 of meisosis

homologous chromosomes separate

step 3 of meisosis

sister chromatids separate

phase when a cell is not dividing, phase where most of the cell cycle is spend

interphase

why is DNA packing necessary

DNA is getting ready to move and doesn't want to leave anything behind

amount of chromosomes the human body has

46

cancer and mitosis relate

cancer is when mitosis fails to stop

mutations and cancer relate

cancer develops from a mutated cell which creates a tumor

carcinogen

something that alters the DNA sequence

example of carcinogens

pesticides, tobacco

cancer metastasis meaning

cancer cells spread to other parts of the body

Henrietta Lacks

died of cancer, cells harvested and survived outside of the body

HeLa cells

helped with lots of medical discoveries

amount of chromosomes in human gametes

23

karyotype

a visual, ordered display of all the chromosomes from one body cell (excluding sex cells)

monosomy

missing a chromosome (45 instead of 46)

karyotypes used for

used to see chromosomal abnormalities, determine biological sex (male - XY, female - XX)

trisomy

extra chromosome (47 instead of 46)

Down syndrome

Trisomy 21

klinefelter's syndrome

trisomy x, small testes that do not produce as much testosterone (only male)

turner syndrome

monosomy x, results in down turning eyelids, prominent ears, heart/liver abnormalities

amount of cells resulted from meisosis

4, not genetically identical

difference between mitosis & meisosis

Mei has 2 divisions, mitosis produces genetically identical cells, meiosis produces gametes with half the number of chromosomes

similarities between meiosis and mitosis

they both make cells, have centrioles, have a spindle, have a nuclear membrane, have interphase, and start with a diploid cell, both are classified as cell division

daughter cells

new cells produced by cell division

possible sources of mutations

inherited, mistake in DNA replication, environment (UV, carcinogen, x-rays)

cytokinesis

when the cytoplasm splits

homoglous chromosomes come from

1 come from each parent

autosome

chromosome that is not a sex chromosome

sex chromosome

pair 23