Mitosis and Meiosis

Centrioles are found only in ______ cells

animal

main difference between meiosis in animal cells and plant cells

animal cells form gametes and plant cells form spores

mutations

any change to DNA Mutations are heritable, permanent changes that are passed on to the next generation of cells when the cell divides.

is mitosis sexual or asexual?

asexual

why do siblings look different even though they have the same parent?

because of crossing over

does chromosomal replication take place before or after division for meiosis?

before

does chromosomal replication take place before or after division for mitosis?

before

__________ is when a new individual splits off from existing ones

budding

Meiosis II involves the separation of __________

chromatids

what does homologous mean?

chromosomes that are identical in size and shape

deletion

complete loss of DNA

haploid

daughter cells with half the number of chromosomes as the parent cell... these cells are the gametes, or sex cells, and are also referred to as sperm and egg.

does meiosis create genetically identical or different daughter cells?

different

does meiosis start with a haploid or a diploid?

diploid

does mitosis end with a haploid or a diploid?

diploid

does mitosis start with a haploid or a diploid?

diploid

how are mitosis and meiosis different

during meiosis, cells undergo two divisions (meiosis I and II), resulting in daughter cells with half the number of chromosomes as the parent cell there are two cell divisions that create 4 daughter cells instead of just 2.

__________ is when a parent separates into 2 or more individuals of equal size.

fission

__________ is when the body of a parent breaks into several pieces and may later develop into a complete individual by growing their missing parts.

fragmentation

does meiosis end with a haploid or a diploid?

haploid

Meiosis I involves the separation of pairs of __________ __________

homologous chromosomes

Sexual reproduction may have originated as a way for cells to __________ __________ _____.

repair damaged DNA

is meiosis sexual or asexual?

sexual

why is it important for the DNA in a cell to be completely replicated prior to meiosis?

so each cell will have the right number of chromosomes

does crossing over always occur?

yes, it always occurs to ensure genetic diversity

how many daughter cells does mitosis create?

2

how many divisions does meiosis have?

2

meiosis... simple

2 divisions, 4 stages each makes sex cells (gametes) 2n ---> 1n

The skin cell of a mouse has 40 chromosomes. How many chromosomes would the egg cell of that mouse have?

20

how many daughter cells does meiosis create?

4

A dog has 39 chromosomes in the sperm cells. How many chromosomes would a dog's zygote contain?

78

meiosis 2

During meiosis II, the cell will complete a second round of cell division to the two cells that were produced during meiosis I. However, during meiosis II, there is no crossing over that takes place and the replicated sister chromatids are now separated. After meiosis II, 4 haploid (n) daughter cells are produced, each containing only one of each type of chromosome.

meiosis 1

During the first cell division, or meiosis I, the homologous chromosomes pair up and exchange sections of their chromosomes. This process is called crossing over and is one of the main reason that there is so much genetic diversity between the parents, offspring, and siblings. Crossing over makes sure that none of the chromosomes present in the daughter cells are identical to each other. After crossing over takes place, the homologous sets of chromosomes are pulled to the opposite poles of their cells. Meiosis I ends with a cell division that creates two cells, each containing a replicated chromosome still held together by a centromere. However, the two homologous chromosomes are now separated into two different cells.

in what two ways does sexual reproduction create greater genetic variety?

First, an offspring inherits DNA from both of its parents. This causes new random combinations of alleles, resulting in a variety of traits that differ from the mother and father. Since genes are randomly assorted when they are passed to offspring, even two siblings have different combinations of genes and traits from the same set of parents. Only identical twins have exactly the same DNA.

What are the three forms of RNA used in protein synthesis?

Transfer RNA Ribosomal RNA Messenger RNA

The process of synthesizing proteins by linking amino acids together from the mRNA strand is known as-

Translation

point mutations

They occur in a single area of DNA. One type of point mutation is a substitution.

replication

This biological process occurs in all cells and will create an exact replica of the original cell. Because DNA replication will make exact copies, it does not allow for genetic variability within a population. However, even this highly regulated process may have errors, in which case mutations can occur.

how are mitosis and meiosis similar?

meiosis is similar to mitosis in that chromosomes replicate and divide into daughter cells

translocation

non-homologous chromosomes attaching to another chromosome

eukaryote

organism with a membrane-bound nucleus that contains DNA

homologous chromosomes

pairs of chromosomes containing the same genes but possibly different alleles

gene knockout

the process by which a gene in an organism is made nonfunctional by a directed mutation. This process can help scientists understand the function of a gene.

what is the purpose of meiosis?

to create gametes with genetic variability for use in sexual reproduction. These gametes, or the sperm and egg, are then used in the process of fertilization to create a zygote. to provide genetic diversity in the offspring and to reduce the number of chromosomes in each sex cell from diploid to haploid (a haploid has only one set of each chromosome).

why do the two cell visions create 4 daughter cells instead of just 2?

to make sure that each daughter cell is a haploid (n). In normal somatic cells, or the body cells, a human has 23 sets of chromosomes or 46 chromosomes in total. Each set of homologous chromosomes contains one chromosome from the father and one from the mother. These cells are considered diploid (2n). However, because of the two cell divisions during meiosis, each daughter cell would only contain 23 total chromosomes because they are no longer paired up in sets. The purpose of this is so that during fertilization, or the fusion of the sperm and egg, a diploid zygote is formed with the correct number of chromosomes. If meiosis does not separate the chromosomes correctly, this can cause many different developmental problems for the growing fetus.

diploid

two haploid cells combine, giving the offspring a complete set of chromosomes

cancer

uncontrollable cell division in the body.

inversion

when genes are placed in a reverse order in a chromosome

duplication

when genes are repeated on a chromosome

benefits of asexual reproduction

-no travel -uses less energy

how many divisions does mitosis have?

1

The random distribution of homologous chromosomes during meiosis is called __________ __________ and occurs during __________ ___ and ___

1) independent assortment 2) metaphase 1 3) metaphase 2

What is the term for a set of three nucleotides?

Codon

In transcription, where does the newly transcribed mRNA strand go in order to be joined with the rRNA for translation?

Cytoplasm

A nucleotide is a small molecule comprising a 5-carbon sugar (deoxyribose, in DNA), a phosphate group, and a nitrogenous base. What distinguishes one nucleotide from another?

The nitrogenous base

fertilization

When gametes (sperm and eggs) join Results in diploid zygote

mitosis

a form of cell division in which the material from the cell nucleus divides

prokaryote

a simple organism that does not have a membrane-bound nucleus or other organelles; most are unicellular; bacteria are an example of a prokaryote

frame-shift mutation

a single nucleotide is added to or deleted from the DNA sequence. This causes a shift in what is called the reading frame. Because DNA is read three bases at a time in a ribosome, an insertion or deletion can cause the wrong amino acids to be added to the chain. This usually results in the assembly of a nonfunctional protein.

asexual reproduction

a single parent produces offspring that are genetically identical to the parent and to each other (mostly associated with prokaryotes)

if a diploid sperm fertilized a diploid egg what would it produce?

a tetraploid

what is crossing over?

homologous chromosomes line up at the center of the cell. When this happens, sections of the homologous chromosomes can cross over and switch positions with other chromosomes. This results in a reshuffling of genes on the individual chromosomes, which provides an even greater variety of genetic combinations that can be passed on to the offspring. During prophase I of meiosis, the replicated paternal and maternal homologous chromosomes intertwine and exchange different sections of their chromosomes, i.e. swap genetic information. The sections that are exchanged contain genes that hold the instructions to code for different traits. The resulting chromosomes that are segregated into daughter cells will contain chromosomes that contain part maternal and paternal genes. This crossing over of homologous chromosomes during meiosis generates many new combination of alleles in the gametes (sperm & egg cell).

does mitosis create genetically identical or different daughter cells?

identical

meiosis

increases genetic variation in organisms that undergo sexual reproduction.

why are the daughter cells that are created all genetically different after meiosis?

the chromosomes randomly sort into the four different daughter cells.

interphase

the chromosomes replicate makes sure that each chromosome is composed of two sister chromatids held together by a centromere. Besides DNA replication, the cell is also growing in size, synthesizing proteins, and going through various check points to make sure that there have not been any errors, or mutations, in the replication process.

what happens when eukaryotes reproduce sexually?

the gametes from each parent join together. The two haploid cells combine, giving the offspring a complete set of chromosomes

meiosis only takes place in the...

the gametes, or sex cells

genetic variation

the measure of the differences among individuals within a population