Mitosis/Meiosis

S Phase of cell cycle

"synthesis" phase double (replicate) DNA

If a sperm of this type fertilized an egg of this type, and both the sperm and egg contributed all of their chromosomes to a zygote, how many chromosomes would the resulting zygote have?

184

during meiosis there are __ cell division

2

if a human egg receives two copies of a chromosome, and this egg is fertilized by a normal sperm, how many copies of this chromosome would there be in the resulting zygote

21

each human cell has __ pairs of homologous chromosomes

23

obliviously, if they body used mitosis to make sperm and eggs, the resultant zygote would have too many chromosomes to produce a normal baby. To produce a normal zygote , how many chromosomes should a sperm and egg have?

23

tetrad

4 chromosomes 2 pairs of sister chromatids

In humans, how many chromosomes should a zygote have, so the baby's body cells will have a normal set of chromsomes

46 chromosomes 23 pairs of homologous chromosome

remember that a typical cell in your body has 46 chromosomes (23 pairs of homologous chromosomes) suppose that human sperm and eggs were produced by mitosis. How many chromosomes would each sperm or egg have?

92

what phases of the cell cycle does interphase include

G1 Phase S Phase G2 Phase

prophase 1

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cell function

a cell cannot function properly when there are too many copies of some proteins due to an extra copy of one of the chromosomes. When the cells in an embryo do not function properly, the embryo develops abnormalities.

karyotype

a photograph or a magnified view of the chromosomes from a human cell, with pairs of homologous chromosomes arranged next to each other and numbered.

gene

a segment of the DNA molecule that gives the instructions for making a protein. For example, one gene gives the instructions for making a protein enzyme which helps to make the pigment melanin, a molecule that contributes to our skin and hair color

what cells in our body are diploid

all the rest practically

checkpoints in the cell cycle

along the cell cycle, there are checkpoints to check if the cell is growing correctly, replicating DNA correctly, and doing everything it's supposed to do correctly before it divides

next, the two sister chromatids of each chromosome are separated. After they separate, each chromatid is an independent chromosome. what is this phase of mitosis called?

anaphase

what process of meiosis results in an extra copy of chromosomes

anaphase, because non disjunction occurs, and sister chromatids do not separate, making 2 chromatids go to one side, and one having none. When the gamete with 2 chromatids combines with another w/ one, you would have 3 chromatids.

gametes

are haploid- they have half as many chromosomes as a normal cell

how does a child have different genetic make up than either parent

arrangement of different alleles different zygote development meiosis creates haploid cells

chromosome combinations

as a result of the different ways that the 23 pairs of homologous chomosomes can line up during Meiosis I, more than 8 million different combinations of chromosomes could be found in the different eggs or sperm produced by one person. If each different type of egg from one mother could be fertilized by each different type of sperm from one father, they could produce zygotes with approximately 70 trillion combinations of chromosomes!

down syndrome

babies born with an extra copy of chromosome 21 in each cell. Down syndrome is the result, with multiple abnormalities, including mental retardation, a broad flat face, a big tongue, short height, and often heart defects.

growth hormones in cancer cells

cancer cells have the ability to secrete their own growth hormone- blood vessels divert over to the cancer cells and supply them with nutrients, giving them supplies to keep growing out of control, and keeps nutrients from healthy cells

anaphase (mitosis)

centromeres connecting sister chromatids break down sister chromatids are pulled apart

DNA is wound tightly into compact chromosomes (each with two sister _____). These compact chromosomes are easier to move than the long thin chromosomes in a cell which is not undergoing cell division. Spindle fibers which will move the chromosomes begin to form

chromatids

spindle fibers putt the sister _____ apart to form separate chromosomes which are moved toward opposite ends of the cell

chromatids

cell in interphase:

chromatin has a nucleus: a lot of DNA (chromatin form)

why is it important that chromatin condense into chromosomes before dividing?

chromatin could tangle when separated into two groups

the two copies of each DNA molecule are attached to each other. Why can't you see the two copies of each DNA molecule at this point

chromatin is non-condensed, making it hard to see

prophase (mitosis)

chromosomes condense centrioles move to opposite sides of the nucleus and the spindle forms nuclear envelope (membrane) breaks down

metaphase (mitosis)

chromosomes line up across the center of the cell each centromere is connected to a spindle fiber

telophase/cytokinesis (mitosis)

chromosomes lose distinct shape nuclear envelope is reformed END OF MITOSIS Mitosis followed by cytokinesis (division of cytoplasm)

chromosome

contains a long molecule of DNA. This molecule of DNA contains many genes

in a process called _____, the cell begins to pinch in half, with one set of chromosomes in each half

cytokenesis

two _____ cells are formed. Each ____ cell has received a complete set of chromosomes. Each chromosome unwinds into a long thin thread so that genes can become active and give the instructions for making proteins

daughter; haploid

alleles

different versions of the same gene. Different alleles give the instructions for making different versions of the protein, and different versions of the protein can result in different characteristics

normal cells are _____

diploid; they have a full set of chromosomes. for humans, normal cells have 46 chromosomes (2n=46)

meiosis definition

division of cells to produce gametes (reproductive cells)

cytokinesis

division of cytoplasm

homologous chromosomes

each cell in your body has two copies of each chromosome, these are those two copies. The DNA in both homologous chromosomes contains the same genes at the same locations in the chromosome. However the two homologous chromosomes may have different versions of a gene

beginning of mitosis

each copy of the DNA is wound tightly into a compact chromosome, and the two chromatids in each chromosome are attached to each other at the centromere. The two chromatids are called sister chromatids because they are identical

embryo

eventually becomes a baby

nondisjunction

genetic problem in process of meiosis

what needs to happen before cells are ready for mitosis

go through interphase: grow and replicate DNA

cell division is needed for ___

growth

G1 Phase of the Cell Cycle

growth phase prepares for DNA replication

G2 phase of cell cycle

growth phase that prepares for division

frequency of mitosis depends on the kind of cell

hair cells divide frequently, while brain cells/neurons don't perform mitosis

gametes in humans

have 23 chromosomes (n=23)

meiosis 1 contains what kind of chromosomes

homologous

pair of similar chromosomes

homologous

daughter cells

identical

apoptosis

if a cell fails its checkpoint, the cell does apoptosis, where the cell destroys itself, it self destrcuts

If cells are always doing mitosis, they're always dividing

if this is the case, they can't carry out their natural function

histone proteins

in the first step of DNA compaction, DNA is wrapped around histone proteins

cells in your body are either in ____ or _____

interphase; mitosis

Meiosis II

is like mitosis, since the sister chromatids of each chromosome are seperated. As a result, each daughter cell gets one copy of a chromosome from the pair of homologous chromosomes that was in the original cell

what happens to the DNA after the DNA wraps around proteins?

it starts to coil and then turns into chromatin fiber, and eventually eventually becomes apart of chromosomes

Almost all the cells in your body were produced by mitosis. The only exception is sperm or eggs which are produced by a different type of cell division called ________

meiosis

meiosis 1

meiosis 1 is different from mitosis because homologous chromosomes line up next to each other and then the two homologous chromosomes separate. This produces daughter cells with half as many chromosomes as the parent cell, i.e. haploid cells. Notice that each daughter cell has a different chromosome from the homologous pair of chromosomes

why can brothers and sisters have different characteristics

meiosis and fertilization result in a different combination of alleles in each child

At the beginning of mitosis, each chromosome consists of a pair of chromatids, and the chromosomes are lined up in the center of the cell. What is this phase of mitosis called?

metaphase

during which phase of meiosis do tetrads line up at the equator

metaphase 1

is cancer contagious?

no, anyone can develop it

M phase of cell cycle

nuclear division

cell division

one cell divides to form two new cells, then each of these cells divides resulting in a total of four cells, etc.

zygote

produces through fertilization; contains chromosomes from both the sperm and egg, and undergoes mitosis to begin the development of the embryo which eventually becomes a baby

meiosis overview

production of haploid gametes (n) from diploid (2n)

when does crossing over occur

prophase 1

meiosis

reduces the number of chromosomes by half, and produces four haploid daughter cells Ex. in humans, each sperm and egg produced by meiosis has only 23 chromosomes , including one chromosome from each pair of homologous chromosomes

In preparation for mitosis, DNA is copied; this is called DNA ____

replication

goal of meiosis 1

separate homologous chromosomes

goal of meiosis 2

seperate sister chromatids

identical chromosomes

sister chromatids

meiosis 2 contains what kind of chromosomes

sister chromatids

mistake in meiosis

sometimes meiosis doesn't happen perfectly, so the chromosomes are not divided completely equally between the daughter cells produced by meiosis. For example, an egg or a sperm may receive two copies of the same chromosome

what cells in our body are haploid

sperm and egg

fertilization

sperm and egg unite to form a single cell called the zygote which contains chromosomes from the sperm and egg. The zygote undergoes mitosis to begin the development of the embryo which eventually becomes a baby

_______ attach to the chromosomes and line the chromosomes up in the middle of the cell

spindle fibers

nucleosome

structure that consists of DNA wrapped around proteins

chemotherapy

targets cells that go through the cell cycle quickly (why someone would lose their hair)

anaphase 1

tetrad is pulled apart

cytokinesis..

the cell begins to pinch together in the middle. Cytokinesis proceeds to produce two separate daughter cells

what happens when a cell has three copies of a chromosome?

the extra copies of the genes on this chromosome result in abnormal cell function and abnormal embryonic development. To understand how an extra copy of one chromosome could result in abnormalities, remember that each chromosome has genes with the instructions to make specific types of proteins, so the extra chromosome could result in too many copies of these specific proteins.

mitosis

the type of cell division that produces almost all the cells in our bodies. In mitosis, one cell divides to produce to identical daughter cells. Each of the daughter cells needs to have a complete set of chromosomes containing an exact copy of all the DNA in the original cell

purpose of apoptosis

to ensure that you don't have messed up cells continue on and divide, because they might not do what they're supposed to-they might start to grow out of control and not be regulated correctly

preparation for mitosis

to get ready for mitosis, the cell makes a copy of the long strand of DNA in each chromosome (DNA replication). This occurs during the S phase of the cell cycle (interphase)

mitosis completed

two new daughter cells have been formed. Each daughter cell has received one copy of each chromosome, so each daughter cell has a complete copy of all the DNA in the original cell

major cause of cancer

uncontrolled cell growth (some cancers have genetic links, making someone more likely to develop it

Each of these pairs of homologous chromosomes has its own ___ set of genes

unique

fertilization overview

when an egg and sperm are untied during fertilization, the resulting zygote has 23 pairs of homologous chromosomes, one in each pair from the egg and one from the sperm. Thus the zygote has 46 chromosomes, and when the zygote undergoes mitosis to begin to form an embryo , each cell will have the normal number of 46 chromosomes

crossing over

when gametes from one chromatid swap places w/ genes from another chromatid benefit: it increases genetic variation

crossing over

when the chromosomes between a mother and father cell cross over and the mom chromosome has some of the dad chromosome, and the dad chromosome has some of the moms

female chromosome

xx

human male chromosomes

xy

at the end of meiosis

you start with one diploid cell and you end up with 4 haploid cells (different versions of chromosome 1 and 2)

cancer cells

your body's own cells that are growing out of control. Not following the rules of the checkpoints, going through the cell cycle, frequently doing mitosis, dividing very often. By doing that, they grow into tumors, which are masses of cancer cells

you can see why no two people are genetically alike, except for identical twins who both develop from the same ____

zygote