cell differentiation/chromosomes test review

what is cell differentiation?

• the process of unspecialized cells becoming specialized to do specific jobs

what are examples of cell differntiation?

• white blood cells

• fat cells

• nuerons

why do cells specialize?

• for cells to be able to do certain jobs for the cell (communicating w/ other cells, aiding organism, etc)

• allow different cells to perform different functions to help the overall survival/function of the organism

totipotent defintition

stem cells that are formed from its first few cell divisions

• can develop into ANY other cell type AND placenta

totipotent ex

fertilized egg/zygote

multipotent definition

limited in potency, can only become the cell type within a specific tissue, multiple cells

multipotent ex

brain, hair follicles, muscles (in adults)

pluripotent definition

formed from totipotent stem cells as they start to differentiate (divide more and more), which eventually makes them pluripotent

• can develop into MOST (not all) of the body’s cell types, NOT placenta

pluripotent ex

blastocyst, umbilical cord

what are differentiated cells?

• cells that result from cell differentiation and that are specialized to do a specific function

ex. red blood cells, skin cells, neurons

independent assortment definition

• happens during anaphase 1 and 2

• chromosomes separate without regard for other non-homologous chromosomes

what are the phases of meiosis in order?

PMAT + cytokinesis

PMAT 2 + cytokinesis 2

prophase I

• chromosomes condense ans thicken

• chromosomes also line up with their homologous pairs

metaphase I

• chromosomes move to the middle of the cell (in pairs); NOT in a single file line

anaphase I

• chromosome pairs are pulled from the spindle fibers

telophase I

• 2 newly formed cells (nuclei)

cytokinesis I

splitting the cytoplasm

prophase II

• doesnt have homologous pairs

• doesnt cross over

metaphase II

• chromosomes line up in the middle in a SINGLE FILE

anaphase II

• sister chromatids are separated by the spindle fibers

telophase II

• nuclei/cells reform

• 2 cells divide to create 4

cytokinesis II

completely splits cytoplasm

what leads up to the formation of haploid cells in meiosis?

• meiosis starts out with diploid, which is then divided through PMAT to make haploid

haploid definition

1 set of chromosomes

diploid definition

2 sets of chromosomes

meiosis v mitosis

meiosis

• creates sex cells, genetic diversity

• unique cells, PMATx2

• sexual reproduction, makes haploids

both

• goes through PMAT

mitosis

• creates human cells (somates)

• repairs damaged cells

• PMATx1

• asexual reproduction

• identical cells

• creates diploids

what is a rule about haploids?

• haploids can only match with another haploid

meiosis in males

• sperm can only be produced AFTER puberty

• creates 4 gametes (sperm) each cycle of meiosis

• division is symmetrical

meiosis in females

• females only born with a certain amount of cells for life

• creates 1 oocyte/egg (that is fertilized)

• the other 3 cells that are produced are polar bodies + not fertile/viable

• division is asymmetrical

meiosis in female v male ex

asexual v sexual reproduction

asexual

ex. mitosis (DNA replication)

• 46 chromosomes

• goes through PMAT x1

sexual

ex. meiosis (DNA duplicates)

• 46 chromosomes

• goes through PMAT x2

internal fertilization

• sperm fertilizes egg inside female body

ex. mammals, birds, reptiles

external fertilization

• egg/sperm releases outside of the body, (usually in water)

ex. fish, amphibians

what are the advantages of internal fertilization?

• higher survival rate

• works on land

• parental care (more of it)

what are the disadvantages of internal fertilization?

• fewer offspring

• more energy per offspring

• risk to parents

what are the advantages of external fertilization?

• lots of offspring

• less energy per offspring

what are the disadvantages of external fertilization?

• low survival rate

• wasted gametes

• works only in aquatic environments

what is the difference between monozygotic and dizygotic twins?

monozygotic = 1 egg, identical

dizygotic = 2 eggs, fraternal

monozygotic v dizygotic twins ex

what are chromosomes made up of?

• made up of 2 identical chromatids

• DNA and proteins

when does the formation of chromosomes happen?

• during prophase I

how many chromosomes does a human have?

46 in total, can vary if there is chromosome anomalies

female chromosomes

XX

male chromosome

XY

how does nondisjunction occur?

• when homologous pairs don’t separate properly and if they don’t go into different cells (meiosis I)

• sister chromatids are supposed to slide apart and if they don’t, that is nondisjunction (meiosis II)

how is sex determined?

• by chromosomes

• SRY Gene (if active, male)

prophase 1 picture

anaphase II picture

metaphase II picture

cytokinesis/telophase II picture

what are 2 events in meiosis that lead to genetic diversity?

• independent assortment

• crossing over

after fertilization, is a cell a diploid or haploid?

diploid

the purpose of meiosis is to ___ chromosomes and ___ genetic material

reduce, recombine