مراجعة داعمة هيكل امتحان الأحياء الصف العاشر عام الفصل الثاني
What limits the size of the cell
> Ratio of surface area to volume
The ratio of surface area to volume is high in smaller cell size
The ratio decreases as the cell voll grows bigger
810.3.1.03.037 use the information collected from md electronic its in the differentiated celluar orgmlzation Of the living may if the abnormal cells were allowed to
STAGES IN CELL CYCLE
>INTERPHASE
• Gap I-Cell grows and perform normal functions
• S-synthesis- DNA is replicated(copied)
• Gap 2- Cell prepares for mitosis
MITOSIS- Cell's nucleus divides and move to opposite end
CYTOKINESIS- Cell divides into two daughter cells with identical nuclei
• What controls the cell cycle
>CycIin and CDK( Cyclin dependent kinase
The checkpoints monitor the cell cycle for errors
• Gl check point- monitors for DNA damage
S checkpoint- Monitor error during replication of DNA
• G2 checkpoint- Monitor error in replicated DNA
M checkpoint —spindle check point detects failure in spindle fibres
rate Of cell division in cancerous videos or imges Of ttüs rate Of cell on an organism
CANCER
• Uncontrolled cell growth and division
Failure in cell cycle regulation Features of cancer cells
• Cancer cell spend less time in interphase
They have abnormal and irregular shape Causes of cancer
• Mutation of DNA
• Carcinogens- substance that cause cancer
How cancer spread from one body part to another
Cancer cells that enter blood vessels are carried to another part of the body
STEM CELLS
Unspecialised cells that can develop into specialized cells
Types of stem cells
• Embryonic stem cell- stem cells in embryo
Adult stem cell- found in various tissues in body and are used to maintain and repair same type of tissues
Research with adult stem cells are less controversial than research with embryonic stem cells
Figure 13 Because stem cells are not locked into becoming one particular type of cell, they might be the key to curing many medical conditions and genetic defects
Musck cel Figure 14 Research with adult stem cells has led to advances in treatments for numerou injuries and diseases
BIOS. 1.03.02S mticelluar organisms as a
sirwle cell (fertilized eu) that qxcessively to many cells with each parent cell passing identical genetic materials to cells
A -low are gametes produced Meiosis
What happens to number of chromosome during meiosis
During Meiosis diploid cell (2n) produces gametes with half number of chromosomes (n)
> What happens to number of chromosomes after fertilization
Haploid male gamete + Haploid female gamete = Diploid zygote
Pg102
F,1 and F2 generations When grew æeds from crms between all of the resulting spring yelkw seeds The this P cress are called filial (F) trait to have disappeared in F. generatkm. and Mendel to investigate whether trait was m:' longer cg whether it was masked Fu of yellow seeds. alkwed the plants to grms' and selffrtilize- and then examined seeds from the resuhs filial (F 2) offspring from F. crcss—are shown in Mendel collected
6022 were yellow and 2CXI were green. which alnost is of yelk»w to green Merujel studied seven different traits—seed pea color. flower
col Fxxi color. seed shape or texture. seed pod stem length. tuwer found that the Fa plants from tiwse croses also smwed a ratio Genes pairs Merdel concluded that trwre must two forms of trait in the pea plants—yellowseed and greensee&and that each was controlled by a factor. which is called an alkk. An allele is &fined as an alternative of a gene passed from generation to gelErati.n. yellow and the gene for green seeds are each forms of a Single gene concluded that ratio during his experi- «xald explained if the alkles were paired in each of the He called from of trait that appeared in the Ftion and of trait the was masked in Fi recessive. In the between yellowseed and green-æed plants the yellow was the xninant trait and the green seed was the recessive form the trait
Pg 106
Punnett square—dihybrid cross Now examine the Punnett square in Figure 13. Notice that in the cross, only two types of alleles are produced However, in the dihybrid cross—when the Fl gen- eration is crossed—four types of alleles from the male gametes and four types of alleles from the female gametes can be produced. The resulting phenotypic ratio is 9:3:3:1—9 yellow round to 3 green round to 3 yellow wrinkled to I green wrinkled. Mendel's data closely matched the out- come predicted by the Punnett square
Probability
The inheritance of genes can be compared to the probability of flipping a coin. The probability of the coin landing on heads is 1 out of 2, or 1 /2. If the same coin is flipped twice, the probability of it landing on heads is 1/2 each time or 1 /2 x 1 /2, or 1 / 4 both times Actual data might not perfectly match the pre - dicted ratios. You know that if you flip a coin you might not get heads 1 out of 2 times. Mendel's results were not exactly a ratio. However, the larger the number of offspring involved in a cross, the more likely it will match the results pre- dicted by the Punnett square