Bio midterm

Mitosis

cell cycle

1. Interphase

2. Mitosis

3. cytokinesis

why the cell divide?

2 part of cell divison:

1. growth and repair

2. reproduction bring babies babies= of spring

   reproduction cell divison types: mitosis and meiosis

mitosis

mitosis is the division of the nucleus of the cell and its content (identical cells)

46 chromosomes in all body cells

chromosomes

they have 2 chromatics 1 centromere( the middle) and they are sister chromatids

sister chromatids are chromatids that form the same chromosome

stages

the longest time in the cell spent in the preparation of cell division = interphase

Interphase

the cell spends 95% of its time in interphase

there are 3 phases in interphase

1. G1 2.S 3. G2

the cell cycle = life cycle of the cell

G0-phase

G0 phase is no cell division

G1-phase

• extra growth

organelles replication

S-phase

S = synthesis

DNA replication

it starts with a mother cell the divides into 2 new doughter cells with 46 chromosomes each equaling 92 chromosomes in both

a mother cell is a cell that is going to divide into 2 creating 2 daughter cells

douplicated = 2 chromatids

unduplicated = single

appers only if the cell divide

G2-phase

preparation for cell division

Mitosis

the only cells that dont undergo mitosis are the nerve cell (brain)

the spindle fibers are used to push the chromosome to the middle of the cell

stages of mitosis

PMAT

• prophase

• metaphase

• anaphase

• telophase

prophase

1. nuclear membrane brake apart

2. chromosomes shorten and condense

3. centrioles move to opposite pole

centrioles move to opposite poles

metaphase

sister chromatids line up in the middle of the cell = cell equator

anaphase

sister chromatids pulled by the spindle fibers to opposite pole

each chromatid now is a seperated chromosome.

telophase

1. nuclear membrame reform

2. 2 new nuclei are formed

3. chromosome un coiled.

cytokinesis

the physical process of separating the cells

animal cell: cleavage furrow is the line between the separating animal cells

plant cells: cells plate is the line between the separating plant cells

DNA

living : have cell

cell: basic unit of life

living thing: organism

oranisims have 1 or more cell

ex: bacteria : 1 cell like plants, animals, humans.

all cells have four things which are : cell membrane cytoplasm DNA and organelles

organelles: tiny organ

DNA is in 1.genetics 2. crops 3. diseases

DNAs full name is deoxyribonucleic acid

how many chromosomes do humans have? 46 and 23 pairs

the DNA is located in the nucleus in the chromosome

nucleus: central part of the cell inside chromosomes

the center of a chromosome is called the centromere and thats where 2 chromatids are linked and half of the cromosome is called a chromatid

the dna is up to 2 meters long

gene : its a segment of dna

female is xx male is xy

the shape of the DNA is called a double helix

the genetic code is to build up protein there are 42 protien and 22 cells build up protien

each chromosome is a very long molecule of tightly coild DNA

gene can be used for skin color eye shape and more like that

all genes that form a person is called genome all genes that make ip an organism

DNA: 1. sugar ribose 2.phosphate group 3. nitrogen base

the 4 bases are adenine and thymine and cytosine and guanine

the ones that pair together are adenine and thymine with 2 dots then cytosine and guanine with 3 dots connecting them

the dots represent the hydrogen bond that connects them together

meiosis

meisosis called reduction divison: reduce the number of chromosomes into half

8 ———> 4 4 4 4

meisis only for sexual reproduction

meiosis makes 4 haploid sex cells which are egg cells (female) and sperm cell (male)

cells that undergo meiosis are called “germ line cells” ←——— sex organs

body cells are: somatic cells → mitosis

there are 46 chromosmes in one cells 44 are autosomes and 2 are sex chromosomes xx for female xy for male

these are types of body cells ( somtic)

• skin cell

• liver cell

• hair cell

autosome: all chromosomes in the cell except sex chromosomes

meiosis division

meiosis 1

stages:

• prophase 1 ( the longest important stage)

• metaphase 1

• anaphase 1

• telophase 1

prophase 1

→ the crossing over takes place in this stage

→ prophase 1 meiosis 1 is the longest stage of the cell division 90%

→ crossing over takes place betweeen unsister chromatids in the homologous chromosomes

→ crossing over leads to the genetic variation

homologous chromosomes

chromosomes found in pairs each inherited from 1 parent

sister chromatids = chromatids of the same chromosome

tetrad = 4 chromatids

gametes

sperm cells from males egg cell from femal 23 chromosomes come from each to create a gamete

dad has xy chromosomes which decides the gender of the kid while mom has xy

they have 44 autosomes and 2 sex chromosomes which decides the gender

zygote is the joining of sperm and egg

example: ahmed has 44 autosomes and 2 sex chromosomes which are xy showing that hes a male

reproduction

the process of cell division of all living organism to produce offspring = baby

asexual: one parent, identical daughter cells (mitosis)

sexual: male and female (meiosis)

types of cells

somatic = body

1. have full number of chromosomes = diploid 2n

2. divide by mitosis

gametes = sex cells

1. have half number of chromosomes = haploid n

2. result of meiosis

gametes = sex cells

sperm (male) and egg (female) 23 chromsomes from each

fertilization

the fusion of sprem and egg cell: zygote (2n) diploid

fertilization: the fusion of gametes

zygote

fertilized egg (diploid) = 46 chromsomes

no of chromsomes in 1 somatic cell = 46 chromsomes =23 pairs

22 pair autosomes 1 pair sex chromsomes xx → female xy → male

karyotyping

1. Trisomy 18 (Edwards Syndrome): This condition involves an extra copy of chromosome 18. It leads to severe intellectual disability, growth deficiencies, and various physical abnormalities. Many affected infants do not survive past their first year.

2. Trisomy 13 (Patau Syndrome): This syndrome is caused by an extra chromosome 13 and is characterized by severe intellectual disability and physical abnormalities, including heart defects and cleft lip/palate. Like Edwards syndrome, it has a high mortality rate in infants.

3. Monosomy X (Turner Syndrome): This condition occurs when one of the X chromosomes is missing or partially missing in females. It results in short stature, delayed puberty, and various medical issues. Turner syndrome does not affect intelligence but can lead to other health complications.

4. Klinefelter Syndrome (47,XXY): This is caused by an extra X chromosome in males and is associated with symptoms such as reduced testosterone levels, infertility, and developmental delays.

5. Down Syndrome (Trisomy 21): As previously mentioned, it results from an extra copy of chromosome 21 and leads to a variety of developmental and health issues.

GMO

GMOs are organisms whose genetic material has been altered using genetic engineering techniques. This process allows scientists to introduce new traits into organisms that would not naturally occur through traditional breeding methods.

Uses of GMOs

• Agriculture: Crops can be modified to enhance yield, increase resistance to pests, diseases, and environmental conditions, or improve nutritional content (e.g., Vitamin A in Golden Rice).

• Medicine: GMOs are used to produce insulin, growth hormones, and vaccines.

• Research: Models like genetically modified mice help in understanding various diseases and conditions.

Benefits of GMOs

• Increased Crop Resilience: GMOs can withstand herbicides and resist pests, leading to lower agricultural losses.

• Reduced Chemical Use: Lower reliance on chemical pesticides can lead to less environmental impact.

• Enhanced Nutritional Content: Some GMOs are designed to have improved nutritional benefits.

Concerns Regarding GMOs

• Health Risks: There are ongoing debates about the long-term health effects of consuming GMOs.

• Environmental Impact: Concerns about biodiversity, potential consequences of gene transfer to non-GMO plants, and the impact on ecosystem balance.

• Ethical Issues: Debates on the morality of altering natural organisms and corporate control of food supply.

Conclusion

GMOs are a controversial topic with significant advancements in technology that hold the potential for improved food security and health but also raise important ethical, health, and environmental questions.